add -fvisibility=hidden to CC flags, mark XXX_main functions
EXTERNALLY_VISIBLE. 5% size reduction of libbusybox.so

diff --git a/coreutils/date.c b/coreutils/date.c
index e33a977..a8e3393 100644
--- a/coreutils/date.c
+++ b/coreutils/date.c
@@ -38,7 +38,7 @@
 		putenv((char*)"TZ=UTC0");
 }
 
-int date_main(int argc, char **argv);
+int date_main(int argc, char **argv) MAIN_EXTERNALLY_VISIBLE;
 int date_main(int argc, char **argv)
 {
 	time_t tm;