Revert r171048, "Cache visibility of decls."

It broke stage2.

git-svn-id: https://llvm.org/svn/llvm-project/cfe/trunk@171050 91177308-0d34-0410-b5e6-96231b3b80d8
diff --git a/lib/Sema/SemaAttr.cpp b/lib/Sema/SemaAttr.cpp
index 3bfb8f2..4406f2d 100644
--- a/lib/Sema/SemaAttr.cpp
+++ b/lib/Sema/SemaAttr.cpp
@@ -309,8 +309,7 @@
   if (!VisContext)
     return;
 
-  NamedDecl *ND = dyn_cast<NamedDecl>(D);
-  if (ND && ND->getExplicitVisibility())
+  if (isa<NamedDecl>(D) && cast<NamedDecl>(D)->getExplicitVisibility())
     return;
 
   VisStack *Stack = static_cast<VisStack*>(VisContext);
@@ -321,7 +320,6 @@
     = (VisibilityAttr::VisibilityType) rawType;
   SourceLocation loc = Stack->back().second;
 
-  ND->ClearLVCache();
   D->addAttr(::new (Context) VisibilityAttr(loc, Context, type));
 }