[OpenMP] Disable several tests with recently uncovered failures (#502)

Flang used to emit errors for uses of deprecated features, or those
introduced in later spec versions. Several tests expected compilation
errors, and these errors from flang made them pass even though they
weren't the errors that the tests originally anticipated.

With the usage errors demoted to warnings by default, these tests
compile successfully with flang leading to failures. Exclude these
tests until the underlying issues are addressed.