Fix build with clang https://bugs.gentoo.org/758167

--- a/md/md.c
+++ b/md/md.c
@@ -148,8 +148,7 @@ static void parse_dep();
 static void save_dot_o();
 
 int
-main(argc,argv)
-register char **argv;
+main(int argc, char** argv)
 {
 int size;