[OpenMP][clang] 6.0: num_threads strict (part 1: host runtime) (#146403)

OpenMP 6.0 12.1.2 specifies the behavior of the strict modifier for the
num_threads clause on parallel directives, along with the message and
severity clauses. This commit implements necessary host runtime changes.

GitOrigin-RevId: 424abcb6413c16762b1d98a31b3530e7651d4155
1 file changed