[NFC] Runtime: Use a range-based for loop.

Replace this direct use of the count in a table header as the upper
bound of a for loop with a range-based for loop over the range which was
being indexed into.  That range was constructed using that count to
begin with.

Author: nate-chandler

stdlib/public/runtime/Metadata.cpp

@@ -3704,9 +3704,7 @@ static void initClassVTable(ClassMetadata *self) {
   if (description->hasOverrideTable()) {
     auto *overrideTable = description->getOverrideTable();
     auto overrideDescriptors = description->getMethodOverrideDescriptors();
-    for (unsigned i = 0, e = overrideTable->NumEntries; i < e; ++i) {
-      auto &descriptor = overrideDescriptors[i];
-
+    for (auto &descriptor : overrideDescriptors) {
       installOverrideInVTable(
           descriptor.Class.get(), descriptor.Method.get(),
           [&descriptor]() { return descriptor.getImpl(); }, overrideTable,