make __init_libc static for non-shared libc

being static allows it to be inlined in __libc_start_main; inlining
should take place at all levels since the function is called exactly
once. this further reduces mandatory startup code size for static
binaries.

src/env/__libc_start_main.c

@@ -22,6 +22,9 @@ weak_alias(dummy1, __init_ssp);
 extern size_t __hwcap, __sysinfo;
 extern char *__progname, *__progname_full;
 
+#ifndef SHARED
+static
+#endif
 void __init_libc(char **envp, char *pn)
 {
 	size_t i, *auxv, aux[AUX_CNT] = { 0 };