[OPENMP50]Add support for if clause for simd part in master taskloop simd directive.

According to OpenMP 5.0, the if clause can be applied to simd
subdirective in the combined directives.
diff --git a/clang/lib/Sema/SemaOpenMP.cpp b/clang/lib/Sema/SemaOpenMP.cpp
index 2523d7e..cacb810 100644
--- a/clang/lib/Sema/SemaOpenMP.cpp
+++ b/clang/lib/Sema/SemaOpenMP.cpp
@@ -4660,6 +4660,8 @@
     Res = ActOnOpenMPMasterTaskLoopSimdDirective(
         ClausesWithImplicit, AStmt, StartLoc, EndLoc, VarsWithInheritedDSA);
     AllowedNameModifiers.push_back(OMPD_taskloop);
+    if (LangOpts.OpenMP >= 50)
+      AllowedNameModifiers.push_back(OMPD_simd);
     break;
   case OMPD_parallel_master_taskloop:
     Res = ActOnOpenMPParallelMasterTaskLoopDirective(
@@ -10688,6 +10690,7 @@
         CaptureRegion = OMPD_parallel;
       break;
     case OMPD_taskloop_simd:
+    case OMPD_master_taskloop_simd:
       if (OpenMPVersion <= 45)
         break;
       if (NameModifier == OMPD_unknown || NameModifier == OMPD_simd)
@@ -10707,7 +10710,6 @@
     case OMPD_task:
     case OMPD_taskloop:
     case OMPD_master_taskloop:
-    case OMPD_master_taskloop_simd:
     case OMPD_target_data:
     case OMPD_simd:
     case OMPD_for_simd: