SQUASHME pthreads/configure.m4: bunches of minor updates

- Use OPAL_VAR_SCOPE_PUSH|POP to make shell variable scopes safe
- Use the "-eq" and "-ne" test operands for numeric comparisons
- Use proper C prototypes in the Fortran link test to prevent spurious
  compiler warnings

Signed-off-by: Jeff Squyres <jsquyres@cisco.com>

Author: jsquyres

opal/mca/threads/pthreads/configure.m4

@@ -10,7 +10,7 @@
 #                         University of Stuttgart.  All rights reserved.
 # Copyright (c) 2004-2005 The Regents of the University of California.
 #                         All rights reserved.
-# Copyright (c) 2008-2013 Cisco Systems, Inc.  All rights reserved.
+# Copyright (c) 2008-2020 Cisco Systems, Inc.  All rights reserved.
 # Copyright (c) 2015      Research Organization for Information Science
 #                         and Technology (RIST). All rights reserved.
 # Copyright (c) 2019      Sandia National Laboratories.  All rights reserved.
@@ -122,7 +122,8 @@ AS_IF([test "$OPAL_THREADS_HAVE_DIFFERENT_PIDS" = "1"],
 # if pthreads is not available, then the system does not have an insane threads
 # model
 #
-OPAL_VAR_SCOPE_POP])dnl
+OPAL_VAR_SCOPE_POP
+])dnl
 
 AC_DEFUN([OPAL_INTL_PTHREAD_TRY_LINK], [
 # BEGIN: OPAL_INTL_PTHREAD_TRY_LINK
@@ -171,6 +172,8 @@ AC_DEFUN([OPAL_INTL_PTHREAD_TRY_LINK_FORTRAN], [
 # Make sure that we can run a small application in Fortran, with
 # pthreads living in a C object file
 
+OPAL_VAR_SCOPE_PUSH([HAPPY opal_conftest_h])
+
 # Fortran module
 cat > conftestf.f <<EOF
       program fpthread
@@ -198,7 +201,12 @@ pthread_t me, newthread;
 
 void cleanup_routine(void *foo);
 void *thread_main(void *foo);
+
 void pthreadtest_f(void);
+void pthreadtest(void);
+void pthreadtest_(void);
+void pthreadtest__(void);
+void PTHREADTEST(void);
 
 void cleanup_routine(void *foo) { i = 4; }
 void *thread_main(void *foo) { i = 2; return (void*) &i; }
@@ -256,8 +264,9 @@ else
     $2
 fi
 
-unset HAPPY opal_conftest_h
 rm -rf conftest*
+
+OPAL_VAR_SCOPE_POP
 # END: OPAL_INTL_PTHREAD_TRY_LINK_FORTRAN
 ])dnl
 
@@ -457,6 +466,7 @@ AC_DEFUN([OPAL_INTL_POSIX_THREADS_SPECIAL_FLAGS],[
 # Put -mt before -mthreads because HP-UX aCC will properly compile
 # with -mthreads (reading as -mt), but emit a warning about unknown
 # flags hreads.  Stupid compilers.
+OPAL_VAR_SCOPE_PUSH([pflags])
 
 case "${host_cpu}-${host_os}" in
   *solaris*)
@@ -480,6 +490,7 @@ AC_PROVIDE_IFELSE([AC_PROG_FC],
                   [OPAL_INTL_POSIX_THREADS_SPECIAL_FLAGS_FC],
                   [opal_pthread_fortran_success=1])
 
+OPAL_VAR_SCOPE_POP
 # End: OPAL_INTL_POSIX_THREADS_SPECIAL_FLAGS
 ])dnl
 
@@ -604,10 +615,10 @@ AC_DEFUN([OPAL_INTL_POSIX_THREADS_LIBS_FC],[
 #
 # Fortran compiler
 #
-if test "$opal_pthread_fortran_success" = "0" && \
+if test $opal_pthread_fortran_success -eq 0 && \
    test "$OMPI_TRY_FORTRAN_BINDINGS" -gt "$OMPI_FORTRAN_NO_BINDINGS" && \
    test $ompi_fortran_happy -eq 1; then
-  if test ! "$opal_pthread_c_success" = "0" && test ! "$TPKG_LIBS" = "" ; then
+  if test $opal_pthread_c_success -ne 0 && test ! "$TPKG_LIBS" = "" ; then
     AC_MSG_CHECKING([if Fortran compiler and POSIX threads work with $TPKG_LIBS])
     LIBS="$orig_LIBS $TPKG_LIBS"
     AC_LANG_PUSH(C)
@@ -654,6 +665,7 @@ AC_DEFUN([OPAL_INTL_POSIX_THREADS_LIBS],[
 # libpthreads: AIX - must check before libpthread
 # liblthread:  LinuxThreads on FreeBSD
 # libpthread:  The usual place (like we can define usual!)
+OPAL_VAR_SCOPE_PUSH([plibs])
 plibs="-lpthreads -llthread -lpthread"
 
 # Only run C++ and Fortran if those compilers already configured
@@ -669,6 +681,7 @@ AC_PROVIDE_IFELSE([AC_PROG_FC],
                   [OPAL_INTL_POSIX_THREADS_LIBS_FC],
                   [opal_pthread_fortran_success=1])
 
+OPAL_VAR_SCOPE_POP
 # End: OPAL_INTL_POSIX_THREADS_LIBS]
 )dnl
 
@@ -679,6 +692,7 @@ AC_PROVIDE_IFELSE([AC_PROG_FC],
 #
 #********************************************************************
 AC_DEFUN([OPAL_CONFIG_POSIX_THREADS],[
+    OPAL_VAR_SCOPE_PUSH([opal_pthreads_result defval opal_pthread_c_success opal_pthread_fortran_success opal_pthread_cxx_success orig_CFLAGS orig_FCFLAGS orig_CXXFLAGS orig_CPPFLAGS orig_CXXCPPFLAGS orig_LDFLAGS orig_LIBS])
     AC_REQUIRE([AC_PROG_GREP])
 
 opal_pthread_c_success=0
@@ -725,8 +739,8 @@ AC_LINK_IFELSE(
     [AC_LANG_PROGRAM(
         [[#include <pthread.h>]],
         [[pthread_mutexattr_settype(NULL, PTHREAD_MUTEX_ERRORCHECK_NP);]])],
-    [result="yes" defval=1], [result="no" defval=0])
-AC_MSG_RESULT([$result])
+    [opal_pthreads_result="yes" defval=1], [opal_pthreads_result="no" defval=0])
+AC_MSG_RESULT([$opal_pthreads_result])
 AC_DEFINE_UNQUOTED([OPAL_HAVE_PTHREAD_MUTEX_ERRORCHECK_NP], [$defval],
             [If PTHREADS implementation supports PTHREAD_MUTEX_ERRORCHECK_NP])
 
@@ -736,8 +750,8 @@ AC_LINK_IFELSE(
     [AC_LANG_PROGRAM(
         [[#include <pthread.h>]],
         [[pthread_mutexattr_settype(NULL, PTHREAD_MUTEX_ERRORCHECK);]])],
-    [result="yes" defval=1], [result="no" defval=0])
-AC_MSG_RESULT([$result])
+    [opal_pthreads_result="yes" defval=1], [opal_pthreads_result="no" defval=0])
+AC_MSG_RESULT([$opal_pthreads_result])
 AC_DEFINE_UNQUOTED([OPAL_HAVE_PTHREAD_MUTEX_ERRORCHECK], [$defval],
             [If PTHREADS implementation supports PTHREAD_MUTEX_ERRORCHECK])
 
@@ -761,23 +775,21 @@ OPAL_CHECK_PTHREAD_PIDS
 
 if test "$OMPI_TRY_FORTRAN_BINDINGS" = "$OMPI_FORTRAN_NO_BINDINGS" || \
    test $ompi_fortran_happy -ne 1; then
-  opal_pthread_fortran_success=1
+    opal_pthread_fortran_success=1
 fi
 
-if test "$opal_pthread_c_success" = "1" && \
-   test "$opal_pthread_cxx_success" = "1" && \
-   test "$opal_pthread_fortran_success" = "1"; then
-  internal_useless=1
-AC_MSG_RESULT("looks like posix threads work")
-  $1
+AC_MSG_CHECKING([if POSIX threads work])
+if test $opal_pthread_c_success -eq 1 && \
+   test $opal_pthread_cxx_success -eq 1 && \
+   test $opal_pthread_fortran_success -eq 1; then
+    AC_MSG_RESULT([yes])
+    $1
 else
-  internal_useless=1
-AC_MSG_RESULT("looks like posix threads don't work")
-  $2
+    AC_MSG_RESULT([no])
+    $2
 fi
 
-unset opal_pthread_c_success opal_pthread_fortran_success opal_pthread_cxx_success
-unset internal_useless
+OPAL_VAR_SCOPE_POP
 ])dnl
 
 AC_DEFUN([MCA_opal_threads_pthreads_PRIORITY], [30])
@@ -826,14 +838,16 @@ AC_DEFUN([MCA_opal_threads_pthreads_POST_CONFIG],[
 # ------------------------------------------------
 AC_DEFUN([MCA_opal_threads_pthreads_CONFIG],[
     AC_CONFIG_FILES([opal/mca/threads/pthreads/Makefile])
+    OPAL_VAR_SCOPE_PUSH([posix_thread_works])
 
     AS_IF([test -z "$with_threads" || test "$with_threads" = "pthreads" || test "$with_threads" = "yes"],
           [OPAL_CONFIG_POSIX_THREADS([posix_threads_works=1],[posix_threads_works=0])],
           [posix_threads_works=0])
 
-    AS_IF([test "$posix_threads_works" = "1"],
+    AS_IF([test $posix_threads_works -eq 1],
           [$1],
           [$2])
-   AC_MSG_RESULT("posix_threads_works = $posix_threads_works")
+
+    OPAL_VAR_SCOPE_POP
 ])