Use intra-DSO calls when we build libbusybox. No-op for normal build.
This was Bernhard Fischer' idea.

   text    data     bss     dec     hex filename
 773549    7781    9740  791070   c121e busybox.t7/0_lib/libbusybox.so.1.11.0.svn_unstripped
 769683    7397    9740  786820   c0184 busybox.t9t/0_lib/libbusybox.so.1.11.0.svn_unstripped

diff --git a/include/grp_.h b/include/grp_.h
index 061b86e..45ee22b 100644
--- a/include/grp_.h
+++ b/include/grp_.h
@@ -21,15 +21,13 @@
  *	POSIX Standard: 9.2.1 Group Database Access	<grp.h>
  */
 
-#if !ENABLE_USE_BB_PWD_GRP
-
-#include <grp.h>
-
-#else
-
 #ifndef	_GRP_H
 #define	_GRP_H 1
 
+#if __GNUC_PREREQ(4,1)
+# pragma GCC visibility push(hidden)
+#endif
+
 /* The group structure.	 */
 struct group {
 	char *gr_name;          /* Group name.  */
@@ -128,6 +126,8 @@
    of which USER is a member.  Also include GROUP.  */
 extern int initgroups(__const char *__user, gid_t __group);
 
+#if __GNUC_PREREQ(4,1)
+# pragma GCC visibility pop
+#endif
 
-#endif /* grp.h  */
 #endif