[OMPT] Align implementation of reenter frame address to latest (frozen) version of OMPT spec

The latest OMPT spec changed the semantic of a tasks reenter frame to be the application frame, that will be entered, when the runtime frame drops.
Before it was the last frame in the runtime. This doesn't work for some gcc execution pathes or even clang generated code for :
Since there is no runtime frame between the executed task and the encountering task.

The test case compares exit and reenter addresses against addresses captured in application code

Patch by Joachim Protze!

Differential Revision: https://reviews.llvm.org/D23305

llvm-svn: 281464