use 'arch -?' to force achitecture selection on macOS

Author: mattip

.gitignore

@@ -17,3 +17,4 @@ local/scipy_openblas64/include
 local/scipy_openblas64/*.so
 local/scipy_openblas64/*.pyd
 local/scipy_openblas64/*.dylib
+objconv/

tools/build_steps.sh

@@ -15,7 +15,9 @@ function before_build {
         source ${ROOT_DIR}/multibuild/osx_utils.sh
         get_macpython_environment ${MB_PYTHON_VERSION} venv
         source ${ROOT_DIR}/gfortran-install/gfortran_utils.sh
-        install_gfortran
+        # Since install_fortran uses `uname -a` to determine arch,
+        # force the architecture
+        arch -${PLAT} install_gfortran
         # Deployment target set by gfortran_utils
         echo "Deployment target $MACOSX_DEPLOYMENT_TARGET"
 
@@ -209,7 +211,7 @@ function do_build_lib {
         echo "Due to the qemu versions 7.2 causing utest cases to fail,"
         echo "the utest dsdot:dsdot_n_1 have been temporarily disabled."
     fi
-    if [ -v dynamic_list ]; then
+    if [ -n "$dynamic_list" ]; then
         CFLAGS="$CFLAGS -fvisibility=protected -Wno-uninitialized" \
         make BUFFERSIZE=20 DYNAMIC_ARCH=1 QUIET_MAKE=1 \
             USE_OPENMP=0 NUM_THREADS=64 \