[OpenMP] Fix data sharing analysis in nested clause

Without this patch, clang doesn't complain that X needs explicit data
sharing attributes in the following:

```
 #pragma omp target teams default(none)
 {
   #pragma omp parallel num_threads(X)
     ;
 }
```

However, clang does produce that complaint after the braces are
removed.  With this patch, clang complains in both cases.

Reviewed By: ABataev

Differential Revision: https://reviews.llvm.org/D55861

llvm-svn: 349635
diff --git a/clang/lib/Sema/SemaOpenMP.cpp b/clang/lib/Sema/SemaOpenMP.cpp
index 38a329a..c207ba9 100644
--- a/clang/lib/Sema/SemaOpenMP.cpp
+++ b/clang/lib/Sema/SemaOpenMP.cpp
@@ -2390,13 +2390,9 @@
   void VisitStmt(Stmt *S) {
     for (Stmt *C : S->children()) {
       if (C) {
-        if (auto *OED = dyn_cast<OMPExecutableDirective>(C)) {
-          // Check implicitly captured variables in the task-based directives to
-          // check if they must be firstprivatized.
-          VisitSubCaptures(OED);
-        } else {
-          Visit(C);
-        }
+        // Check implicitly captured variables in the task-based directives to
+        // check if they must be firstprivatized.
+        Visit(C);
       }
     }
   }