[OpenMP][FIX] Ensure flag to disable de-globalization works properly

If the user disables de-globalization we did not seed the AAHeapToShared
and AAHeapToStack but we still could end up with them through in-flight
lookups. With this patch we disable AAHeapToShared completely if the
user disabled de-globalization. Heap-2-stack is still run though.

Differential Revision: https://reviews.llvm.org/D121059