OpenCL: add driver/frontend support for precompiled headers

llvm-svn: 141516
diff --git a/clang/lib/Frontend/CompilerInvocation.cpp b/clang/lib/Frontend/CompilerInvocation.cpp
index b35bc65..ec65655 100644
--- a/clang/lib/Frontend/CompilerInvocation.cpp
+++ b/clang/lib/Frontend/CompilerInvocation.cpp
@@ -1340,6 +1340,7 @@
       .Case("objective-c++-cpp-output", IK_PreprocessedObjCXX)
       .Case("objc++-cpp-output", IK_PreprocessedObjCXX)
       .Case("c-header", IK_C)
+      .Case("cl-header", IK_OpenCL)
       .Case("objective-c-header", IK_ObjC)
       .Case("c++-header", IK_CXX)
       .Case("objective-c++-header", IK_ObjCXX)