[OpenMP][OMPT] Fix OMPT return address guard for gomp interface

D91692 missed various locations in kmp_gsupport, where the scope for
OMPT_STORE_RETURN_ADDRESS is too narrow, i.e. the scope ends before the OMPT
callback is called in some nested function.

This patch fixes the scoping issue, so that all OMPT tests pass, when the
tests are built with gcc.

Differential Revision: https://reviews.llvm.org/D92121