[CMake] Pass CLANG_VERSION_* variables into later stages

When supporting overriding clang versions we also need to pass those through to the next stage so they remain overridden.

llvm-svn: 282109
diff --git a/clang/CMakeLists.txt b/clang/CMakeLists.txt
index 7efef3c..12f79df 100644
--- a/clang/CMakeLists.txt
+++ b/clang/CMakeLists.txt
@@ -549,6 +549,9 @@
     LLVM_VERSION_MAJOR
     LLVM_VERSION_MINOR
     LLVM_VERSION_PATCH
+    CLANG_VERSION_MAJOR
+    CLANG_VERSION_MINOR
+    CLANG_VERSION_PATCHLEVEL
     LLVM_VERSION_SUFFIX
     LLVM_BINUTILS_INCDIR
     CLANG_REPOSITORY_STRING