Revert "[OpenMP][clang] 6.0: num_threads strict (part 1: host runtime)" (#147379)

Reverts #146403

Author: ro-i

openmp/runtime/src/kmp_runtime.cpp

@@ -1214,12 +1214,6 @@ void __kmp_serialized_parallel(ident_t *loc, kmp_int32 global_tid) {
   // Reset for next parallel region
   this_thr->th.th_set_proc_bind = proc_bind_default;
 
-  // OpenMP 6.0 12.1.2 requires the num_threads 'strict' modifier to also have
-  // effect when parallel execution is disabled by a corresponding if clause
-  // attached to the parallel directive.
-  if (this_thr->th.th_nt_strict && this_thr->th.th_set_nproc > 1)
-    __kmpc_error(this_thr->th.th_nt_loc, this_thr->th.th_nt_sev,
-                 this_thr->th.th_nt_msg);
   // Reset num_threads for next parallel region
   this_thr->th.th_set_nproc = 0;