Fix all -Wmissing-prototypes warnings in x86 defconfig

Signed-off-by: Trevor Keith <tsrk@tsrk.net>
Cc: Sam Ravnborg <sam@ravnborg.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

usr/gen_init_cpio.c

@@ -446,7 +446,7 @@ static int cpio_mkfile_line(const char *line)
 	return rc;
 }
 
-void usage(const char *prog)
+static void usage(const char *prog)
 {
 	fprintf(stderr, "Usage:\n"
 		"\t%s <cpio_list>\n"