[OpenMP] Strip NoInline from known OpenMP runtime functions

This patch strips the NoInline attribute from known OpenMP runtime functions.
This is done so that we can denote certain runtime functions as NoInline to
ensure their call sites are intact so they can be checked by OpenMPOpt. We
don't wan't this noinline attribute to remain for any functions after OpenMPOpt
has been run however.

Reviewed By: jdoerfert

Differential Revision: https://reviews.llvm.org/D106482