Revert "Revert "[pgo] Return updated Flags after adding flags for PGO/AFDO""

This reverts commit 988ff8d1.

Reason for revert: RBE can now handle PGO profiles during remote linking.

Bug: http://b/162702246

Test: m ANDROID_PGO_INSTRUMENT=hwui hwuimacro and check hwuimacro has
      PGO instrumentation.

Change-Id: I724b53dc086923beeb6f4b8903136545d18f4ece