[OMPT] Use frames at different level when using clang version 5 or higher with debug flag

Clang 5 or higher adds an intermediate function call in certain cases when
compiling with debug flag. This revision updates the testcases to work
correctly.

Differential Revision: https://reviews.llvm.org/D40595

git-svn-id: https://llvm.org/svn/llvm-project/openmp/trunk@321263 91177308-0d34-0410-b5e6-96231b3b80d8