Revert "[OPENMP] Fix for parsing OpenMP directives with extra braces, brackets and parens"

These parser changes were redundant. The same or better recovery can be
achieved with a one-line fix to SkipUntil() due to land in the next commit.

This reverts commit r197553.
Fix OpenMP recovery with trailing tokens following the pragma

The recovery was failing due to a missing case in SkipUntil().

Also add back tests from r197553 that were reverted in the previous commit.