[CLEANUP] remove a warning from gcc due to htons() in standard.c

Due to the fact that htons is defined as a macro, it's dangerous
to call it with auto-incremented arguments such as htons(f(++x)) :

src/standard.c: In function 'url2sa':
src/standard.c:291: warning: operation on 'curr' may be undefined

The solution is simply to store the intermediate result an pass it
to htons() at once.
diff --git a/src/standard.c b/src/standard.c
index d245949..0b16296 100644
--- a/src/standard.c
+++ b/src/standard.c
@@ -288,7 +288,8 @@
 			if (!ret)
 				return -1;
 			curr += ret;
-			addr->sin_port = (*curr == ':') ? htons(str2uic(++curr)) : htons(80);
+			addr->sin_port = (*curr == ':') ? str2uic(++curr) : 80;
+			addr->sin_port = htons(addr->sin_port);
 		}
 		return 0;
 	}