reduce # const_casts, no functionality change.

llvm-svn: 67861
diff --git a/clang/lib/AST/DeclBase.cpp b/clang/lib/AST/DeclBase.cpp
index 47059d9..ef9dc76 100644
--- a/clang/lib/AST/DeclBase.cpp
+++ b/clang/lib/AST/DeclBase.cpp
@@ -580,8 +580,8 @@
   return const_cast<DeclContext*>(this)->lookup(Name);
 }
 
-const DeclContext *DeclContext::getLookupContext() const {
-  const DeclContext *Ctx = this;
+DeclContext *DeclContext::getLookupContext() {
+  DeclContext *Ctx = this;
   // Skip through transparent contexts.
   while (Ctx->isTransparentContext())
     Ctx = Ctx->getParent();