Fix CentOS 6 and quantal build failures

Author: svoj

include/my_sys.h

@@ -1000,6 +1000,11 @@ extern ulonglong my_getcputime(void);
 #define MAP_NORESERVE 0 /* For irix and AIX */
 #endif
 
+/* Compatibility with pre linux 3.8 distributions */
+#ifdef __linux__
+#define MAP_HUGE_SHIFT 26
+#endif
+
 #ifdef HAVE_MMAP64
 #define my_mmap(a,b,c,d,e,f) mmap64(a,b,c,d,e,f)
 #else