Fix sparse warnings

Make some functions static and convert func() function prototypes to to
func(void).  Fix declaration after statement, missing declaration and
redundant declaration warnings.

Signed-off-by: Timo Hirvonen <tihirvon@gmail.com>
Signed-off-by: Junio C Hamano <junkio@cox.net>

name-rev.c

@@ -230,8 +230,6 @@ int main(int argc, char **argv)
 				fwrite(p_start, p - p_start, 1, stdout);
 		}
 	} else if (all) {
-		extern struct object **objs;
-		extern int nr_objs;
 		int i;
 
 		for (i = 0; i < nr_objs; i++)