libbb: mark scripted_main() as externally visible

Building with individual binaries enabled fails when embedded
script applets are included:

   /tmp/ccIvMFZg.o: In function `main':
   applet.c:(.text.main+0x20): undefined reference to `scripted_main'

Mark scripted_main() as externally visible.

Reported-by: Yann E. MORIN <yann.morin.1998@free.fr>
Signed-off-by: Ron Yorston <rmy@pobox.com>
Signed-off-by: Denys Vlasenko <vda.linux@googlemail.com>
diff --git a/libbb/appletlib.c b/libbb/appletlib.c
index c15014a..fa19e84 100644
--- a/libbb/appletlib.c
+++ b/libbb/appletlib.c
@@ -770,6 +770,7 @@
 	return -1;
 }
 
+int scripted_main(int argc UNUSED_PARAM, char **argv) MAIN_EXTERNALLY_VISIBLE;
 int scripted_main(int argc UNUSED_PARAM, char **argv)
 {
 	int script = find_script_by_name(applet_name);