Switch from using a lit.cfg-generator variable to the real variable in
the standalone mode. We've changed scoping and sequencing of variables
being defined and that cause this to start to be unset breaking some
cmake users. Thanks to Jordan Rose for the report.

The fix also makes the condition on the preceding line much more
sensible. =D

git-svn-id: https://llvm.org/svn/llvm-project/cfe/trunk@159576 91177308-0d34-0410-b5e6-96231b3b80d8
diff --git a/test/CMakeLists.txt b/test/CMakeLists.txt
index ebf6643..f57343d 100644
--- a/test/CMakeLists.txt
+++ b/test/CMakeLists.txt
@@ -51,7 +51,7 @@
   include(FindPythonInterp)
   if(PYTHONINTERP_FOUND)
     if( LLVM_MAIN_SRC_DIR )
-      set(LIT "${LLVM_SOURCE_DIR}/utils/lit/lit.py")
+      set(LIT "${LLVM_MAIN_SRC_DIR}/utils/lit/lit.py")
     else()
       set(LIT "${PATH_TO_LLVM_BUILD}/bin/${CMAKE_CFG_INTDIR}/llvm-lit")
       # Installed LLVM does not contain ${CMAKE_CFG_INTDIR} in paths.