Add missing OSX builtin define

This commit was SVN r29576.

opal/include/opal/sys/architecture.h

@@ -38,6 +38,7 @@
 #define OMPI_MIPS           0070
 #define OMPI_ARM            0100
 #define OMPI_SYNC_BUILTIN   0200
+#define OMPI_OSX_BUILTIN    0400
 
 /* Formats */
 #define OMPI_DEFAULT        1000  /* standard for given architecture */