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

diff --git a/coreutils/install.c b/coreutils/install.c
index 5162084..4adcadb 100644
--- a/coreutils/install.c
+++ b/coreutils/install.c
@@ -66,7 +66,7 @@
 
 #endif
 
-int install_main(int argc, char **argv);
+int install_main(int argc, char **argv) MAIN_EXTERNALLY_VISIBLE;
 int install_main(int argc, char **argv)
 {
 	struct stat statbuf;