only advertise when choosen

As discussed on the uClibc mailinglist, do not advertise
when not activated.
See this thread:
http://lists.uclibc.org/pipermail/uclibc/2015-February/048766.html

include/gnu-versions.h

@@ -45,7 +45,9 @@
 
 #define _GNU_OBSTACK_INTERFACE_VERSION	1 /* vs malloc/obstack.c */
 #define _GNU_REGEX_INTERFACE_VERSION	1 /* vs posix/regex.c */
+#ifdef __UCLIBC_HAS_GNU_GLOB__
 #define _GNU_GLOB_INTERFACE_VERSION	1 /* vs posix/glob.c */
+#endif
 #define _GNU_GETOPT_INTERFACE_VERSION	2 /* vs posix/getopt.c and
 					     posix/getopt1.c */