connect: use strcmp() for string comparison

Get rid of magic string length constants and simply compare the strings
using strcmp().  This makes the intent of the code a bit clearer.

Signed-off-by: Rene Scharfe <l.s.r@web.de>
Signed-off-by: Junio C Hamano <gitster@pobox.com>

connect.c

@@ -161,8 +161,7 @@ struct ref **get_remote_heads(int in, char *src_buf, size_t src_len,
 			server_capabilities = xstrdup(name + name_len + 1);
 		}
 
-		if (extra_have &&
-		    name_len == 5 && !memcmp(".have", name, 5)) {
+		if (extra_have && !strcmp(name, ".have")) {
 			sha1_array_append(extra_have, old_sha1);
 			continue;
 		}