CMake: Builds a native tblgen when cross-compiling and the user didn't
set LLVM_TABLEGEN.


git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@58953 91177308-0d34-0410-b5e6-96231b3b80d8
diff --git a/CMakeLists.txt b/CMakeLists.txt
index 7f477ad..15dcf7f 100644
--- a/CMakeLists.txt
+++ b/CMakeLists.txt
@@ -139,7 +139,7 @@
 set(LLVM_COMMON_DEPENDS ${LLVM_COMMON_DEPENDS} ${LLVM_LIBS} )
 
 set(LLVM_TABLEGEN "tblgen" CACHE
-  STRING "Native TableGen executable.")
+  STRING "Native TableGen executable. Saves building one when cross-compiling.")
 
 add_subdirectory(utils/TableGen)