mpi/src/Makefile.am: use $(GLOBAL_AM_CFLAGS)

mpi/src/Makefile.am

@@ -21,7 +21,7 @@ BUILT_SOURCES =
 
 CLEANFILES = *.gcno *.gcda *.linkinfo
 
-AM_CFLAGS = -Wall $(STARPU_CUDA_CPPFLAGS) $(STARPU_OPENCL_CPPFLAGS) $(FXT_CFLAGS) $(MAGMA_CFLAGS) $(HWLOC_CFLAGS) -Werror=implicit
+AM_CFLAGS = -Wall $(STARPU_CUDA_CPPFLAGS) $(STARPU_OPENCL_CPPFLAGS) $(FXT_CFLAGS) $(MAGMA_CFLAGS) $(HWLOC_CFLAGS) $(GLOBAL_AM_CFLAGS)
 LIBS = $(top_builddir)/src/@LIBSTARPU_LINK@ @LIBS@ $(FXT_LIBS) $(MAGMA_LIBS)
 AM_CPPFLAGS = -I$(top_srcdir)/include/ -I$(top_srcdir)/src/ -I$(top_builddir)/src -I$(top_builddir)/include -I$(top_srcdir)/mpi/include -I$(top_srcdir)/mpi/src
 AM_LDFLAGS = $(STARPU_OPENCL_LDFLAGS) $(STARPU_CUDA_LDFLAGS)