CONFIG SET server.masterauth aesthetic change.

This is just to make the code exactly like the above instance used for
requirepass. No actual change nor the original code violated the Redis
coding style.

src/config.c

@@ -532,11 +532,7 @@ void configSetCommand(redisClient *c) {
         server.requirepass = ((char*)o->ptr)[0] ? zstrdup(o->ptr) : NULL;
     } else if (!strcasecmp(c->argv[2]->ptr,"masterauth")) {
         zfree(server.masterauth);
-        if (sdslen(o->ptr)) {
-          server.masterauth = zstrdup(o->ptr);
-        } else {
-          server.masterauth = NULL;
-        }
+        server.masterauth = ((char*)o->ptr)[0] ? zstrdup(o->ptr) : NULL;
     } else if (!strcasecmp(c->argv[2]->ptr,"maxmemory")) {
         if (getLongLongFromObject(o,&ll) == REDIS_ERR ||
             ll < 0) goto badfmt;