fix gremlin cloning fix

The revised code returned an uninitialized variable if the new test
failed.

The cloneu() case was ok but this changes it to keep parallel to the
clone_mon() case.

src/makemon.c

@@ -821,8 +821,9 @@ m_initinv(struct monst *mtmp)
 
 /* Note: for long worms, always call cutworm (cutworm calls clone_mon) */
 struct monst *
-clone_mon(struct monst *mon,
-          coordxy x, coordxy y) /* clone's preferred location or 0 (near mon) */
+clone_mon(
+    struct monst *mon,
+    coordxy x, coordxy y) /* clone's preferred location or 0 (near mon) */
 {
     coord mm;
     struct monst *m2;