Frontend: Lift InputKind enumeration to top level.

git-svn-id: https://llvm.org/svn/llvm-project/cfe/trunk@105577 91177308-0d34-0410-b5e6-96231b3b80d8
diff --git a/lib/Frontend/ASTUnit.cpp b/lib/Frontend/ASTUnit.cpp
index 4730bdc..48a6983 100644
--- a/lib/Frontend/ASTUnit.cpp
+++ b/lib/Frontend/ASTUnit.cpp
@@ -332,7 +332,7 @@
 
   assert(Clang.getFrontendOpts().Inputs.size() == 1 &&
          "Invocation must have exactly one source file!");
-  assert(Clang.getFrontendOpts().Inputs[0].first != FrontendOptions::IK_AST &&
+  assert(Clang.getFrontendOpts().Inputs[0].first != IK_AST &&
          "FIXME: AST inputs not yet supported here!");
 
   // Create the AST unit.