dict.c: add casting to avoid compilation warning.

rehashidx is always positive in the two code paths, since the only
negative value it could have is -1 when there is no rehashing in
progress, and the condition is explicitly checked.

src/dict.c

@@ -710,7 +710,7 @@ unsigned int dictGetRandomKeys(dict *d, dictEntry **des, unsigned int count) {
             /* Invariant of the dict.c rehashing: up to the indexes already
              * visited in ht[0] during the rehashing, there are no populated
              * buckets, so we can skip ht[0] for indexes between 0 and idx-1. */
-            if (tables == 2 && j == 0 && i < d->rehashidx) {
+            if (tables == 2 && j == 0 && i < (unsigned int) d->rehashidx) {
                 /* Moreover, if we are currently out of range in the second
                  * table, there will be no elements in both tables up to
                  * the current rehashing index, so we jump if possible.
@@ -788,7 +788,7 @@ unsigned int dictGetSomeKeys(dict *d, dictEntry **des, unsigned int count) {
             /* Invariant of the dict.c rehashing: up to the indexes already
              * visited in ht[0] during the rehashing, there are no populated
              * buckets, so we can skip ht[0] for indexes between 0 and idx-1. */
-            if (tables == 2 && j == 0 && i < d->rehashidx) {
+            if (tables == 2 && j == 0 && i < (unsigned int) d->rehashidx) {
                 /* Moreover, if we are currently out of range in the second
                  * table, there will be no elements in both tables up to
                  * the current rehashing index, so we jump if possible.