Enable use of _Static_assert inside structs and unions in C11 mode (as per C11 6.7.2.1p1).

git-svn-id: https://llvm.org/svn/llvm-project/cfe/trunk@178632 91177308-0d34-0410-b5e6-96231b3b80d8
diff --git a/lib/Parse/ParseDecl.cpp b/lib/Parse/ParseDecl.cpp
index 589723a..990a909 100644
--- a/lib/Parse/ParseDecl.cpp
+++ b/lib/Parse/ParseDecl.cpp
@@ -3093,6 +3093,13 @@
       continue;
     }
 
+    // Parse _Static_assert declaration.
+    if (Tok.is(tok::kw__Static_assert)) {
+      SourceLocation DeclEnd;
+      ParseStaticAssertDeclaration(DeclEnd);
+      continue;
+    }
+
     if (!Tok.is(tok::at)) {
       struct CFieldCallback : FieldCallback {
         Parser &P;