Fix a sandcastle crash due to PGO mode

I'm only 95% convinced that this is the cause of a sandcastle crash.
We're not calling transCounterAddr with sequential translation ids
anymore (apparently) so it's possible that we need to allocate more than
one chunk of new counters.

I ran a sandcastle with this fix applied and it didn't crash, but the
crash wasn't 100% before, so you never know.

Reviewed By: @ottoni

Differential Revision: D1142512

hphp/runtime/vm/jit/prof-data.cpp

@@ -44,7 +44,7 @@ T ProfCounters<T>::get(uint32_t id) const {
 template<typename T>
 T* ProfCounters<T>::getAddr(uint32_t id) {
   // allocate a new chunk of counters if necessary
-  if (id >= m_chunks.size() * kCountersPerChunk) {
+  while (id >= m_chunks.size() * kCountersPerChunk) {
     uint32_t size = sizeof(T) * kCountersPerChunk;
     T* chunk = (T*)malloc(size);
     std::fill_n(chunk, kCountersPerChunk, m_initVal);