Fix to use the right macro

This commit was SVN r705.

src/mpi/interface/c/free_mem.c

@@ -9,7 +9,7 @@
 #include "mpi.h"
 #include "mpi/interface/c/bindings.h"
 
-#if LAM_WANT_MPI_PROFILING && LAM_HAVE_WEAK_SYMBOLS
+#if LAM_HAVE_WEAK_SYMBOLS && LAM_PROFILING_DEFINES
 #pragma weak MPI_Free_mem = PMPI_Free_mem
 #endif