Fix check_loopback()

Add missing htonl() so that check_loopback() actually tests for 127.0.0.1
instead of 1.0.0.127 on little-endian machines.

(cherry picked from commit 58a489c2b3)

src/core/loopback-setup.c

@@ -64,7 +64,7 @@ static int check_loopback(void) {
                 struct sockaddr_in in;
         } sa = {
                 .in.sin_family = AF_INET,
-                .in.sin_addr.s_addr = INADDR_LOOPBACK,
+                .in.sin_addr.s_addr = htonl(INADDR_LOOPBACK),
         };
 
         /* If we failed to set up the loop back device, check whether