Revised menhirLib autoconfiguration (#331)

Since Menhir version 20200123, we need to link with menhirLib.cmxa
instead of menhirLib.cmx.

This commit chooses automatically the file to link with:
menhirLib.cmxa if it exists in the menhirLib installation directory,
menhirLib.cmx otherwise.

To reliably find the installation directory, configure was changed
to record the menhirLib directory in Makefile.config, variable MENHIR_DIR,
instead of a pre-cooked command-line option MENHIR_INCLUDES.

Makefile.extr was adapted accordingly.

Fixes: #329
Closes: #330

Author: xavierleroy

Makefile.extr

@@ -55,7 +55,7 @@ extraction/%.cmo: WARNINGS +=-w -20-27-32..34-39-41-44..45-60
 cparser/pre_parser.cmx: WARNINGS += -w -41
 cparser/pre_parser.cmo: WARNINGS += -w -41
 
-COMPFLAGS+=-g $(INCLUDES) $(MENHIR_INCLUDES) $(WARNINGS)
+COMPFLAGS+=-g $(INCLUDES) -I "$(MENHIR_DIR)" $(WARNINGS)
 
 # Using .opt compilers if available
 

Makefile.menhir

@@ -41,7 +41,11 @@ MENHIR_FLAGS = -v --no-stdlib -la 1
 # Using Menhir in --table mode requires MenhirLib.
 
 ifeq ($(MENHIR_TABLE),true)
-  MENHIR_LIBS = menhirLib.cmx
+  ifeq ($(wildcard $(MENHIR_DIR)/menhirLib.cmxa),)
+    MENHIR_LIBS = menhirLib.cmx
+  else
+    MENHIR_LIBS = menhirLib.cmxa
+  endif
 else
   MENHIR_LIBS =
 endif

configure

@@ -582,8 +582,8 @@ case "$menhir_ver" in
   20[0-9][0-9][0-9][0-9][0-9][0-9])
       if test "$menhir_ver" -ge $MENHIR_REQUIRED; then
           echo "version $menhir_ver -- good!"
-          menhir_include_dir=$(menhir --suggest-menhirLib | tr -d '\r' | tr '\\' '/')
-          if test -z "$menhir_include_dir"; then
+          menhir_dir=$(menhir --suggest-menhirLib | tr -d '\r' | tr '\\' '/')
+          if test -z "$menhir_dir"; then
               echo "Error: cannot determine the location of the Menhir API library."
               echo "This can be due to an incorrect Menhir package."
               echo "Consider using the OPAM package for Menhir."
@@ -677,7 +677,7 @@ MANDIR=$sharedir/man
 SHAREDIR=$sharedir
 COQDEVDIR=$coqdevdir
 OCAML_OPT_COMP=$ocaml_opt_comp
-MENHIR_INCLUDES=-I "$menhir_include_dir"
+MENHIR_DIR=$menhir_dir
 COMPFLAGS=-bin-annot
 EOF