Passthrough compiler launcher

Summary: Not having this seems like an oversight, and makes stage2 builds odd.

Reviewers: ddunbar, dexonsmith

Subscribers: mgorny, jkorous, jdoerfert, cfe-commits

Tags: #clang

Differential Revision: https://reviews.llvm.org/D59032

llvm-svn: 355547
GitOrigin-RevId: 2e754720e211e982597e1faab23eef3e3335ae8f
diff --git a/CMakeLists.txt b/CMakeLists.txt
index 8d43ec9..be9a93d 100644
--- a/CMakeLists.txt
+++ b/CMakeLists.txt
@@ -666,6 +666,8 @@
     LLVM_VERSION_SUFFIX
     LLVM_BINUTILS_INCDIR
     CLANG_REPOSITORY_STRING
+    CMAKE_C_COMPILER_LAUNCHER
+    CMAKE_CXX_COMPILER_LAUNCHER
     CMAKE_MAKE_PROGRAM
     CMAKE_OSX_ARCHITECTURES
     LLVM_ENABLE_PROJECTS