build/pkgs/python3/spkg-configure.m4: If PYTHON_FOR_VENV is configured to build multiarch extensions, set SAGE_ARCHFLAGS to disable it

Author: Matthias Koeppe

build/pkgs/python3/spkg-configure.m4

@@ -75,6 +75,15 @@ SAGE_SPKG_CONFIGURE([python3], [
     dnl POST
     AS_IF([test x$sage_spkg_install_python3 = xno], [
         PYTHON_FOR_VENV="$ac_cv_path_PYTHON3"
+        AS_IF([test "$SAGE_ARCHFLAGS" = "unset"], [
+           AC_MSG_CHECKING([whether $PYTHON_FOR_VENV is configured to build multiarch extensions])
+           AS_IF([[CC="$CC" CXX="$CXX" conftest_venv/bin/python3 -m sysconfig | grep '^\sw*\(C\|LD\)FLAGS *=.*[" ]-arch.* -arch' ]] [>& AS_MESSAGE_LOG_FD 2>&1 ], [
+               AC_MSG_RESULT([yes; disabling it by setting ARCHFLAGS])
+               SAGE_ARCHFLAGS=""
+           ], [
+               AC_MSG_RESULT([no])
+           ])
+        ])
         AS_IF([test "$SAGE_ARCHFLAGS" != "unset"], [
             ARCHFLAGS="$SAGE_ARCHFLAGS"
             export ARCHFLAGS