Makefile.am: fix subdirs orders (mpi needs to be compiled before examples)

Makefile.am

@@ -20,14 +20,14 @@ CLEANFILES = *.gcno *.gcda *.linkinfo
 SUBDIRS = src
 SUBDIRS += tools tests doc
 
-if BUILD_EXAMPLES
-SUBDIRS += examples
-endif
-
 if USE_MPI
 SUBDIRS += mpi
 endif
 
+if BUILD_EXAMPLES
+SUBDIRS += examples
+endif
+
 if BUILD_SOCL
 SUBDIRS += socl
 endif