mpl: pass MPL's CFLAGS back to MPICH

MPL exports additional CFLAGS as MPL_CFLAGS. Only the ones that added
by the MPL configure will be passed. The PAC_CONFIG_MPL macro will add
them to CFLAGS.

confdb/aclocal_modules.m4

@@ -18,6 +18,7 @@ AC_DEFUN([PAC_CONFIG_MPL],[
         PAC_CONFIG_MPL_EMBEDDED
         PAC_APPEND_FLAG([-I${main_top_builddir}/src/mpl/include], [CPPFLAGS])
         PAC_APPEND_FLAG([-I${use_top_srcdir}/src/mpl/include], [CPPFLAGS])
+        PAC_APPEND_FLAG([${MPL_CFLAGS}], [CFLAGS])
         mplsrcdir="src/mpl"
         mpllib="src/mpl/libmpl.la"
     ], [

src/mpl/configure.ac

@@ -29,6 +29,7 @@ LT_PREREQ([2.2.6])
 PAC_PUSH_FLAG([CFLAGS])
 LT_INIT()
 PAC_POP_FLAG([CFLAGS])
+PARENT_CFLAGS=${CFLAGS}
 
 # ----------------------------------------------------------------------------
 # Set default library names if names haven't already been provided
@@ -1405,6 +1406,9 @@ AX_GCC_VAR_ATTRIBUTE(used)
 
 PAC_POP_ALL_FLAGS
 
+MPL_CFLAGS="${CFLAGS#${PARENT_CFLAGS}}"
+AC_SUBST(MPL_CFLAGS)
+
 dnl Final output
 AC_CONFIG_FILES([Makefile localdefs include/mpl_timer.h])
 AC_OUTPUT

src/mpl/localdefs.in

@@ -5,5 +5,6 @@
 
 GPU_SUPPORT="@GPU_SUPPORT@"
 CPPFLAGS="@CPPFLAGS@"
+MPL_CFLAGS="@MPL_CFLAGS@"
 WRAPPER_LIBS="$WRAPPER_LIBS @LDFLAGS@ @LIBS@"
 COMPILER_TLS="@COMPILER_TLS@"