CMake: Use LLVM_MAIN_SRC_DIR instead of CMAKE_SOURCE_DIR, for
consistency.

Patch by Kevin Andre!


git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@59326 91177308-0d34-0410-b5e6-96231b3b80d8
diff --git a/CMakeLists.txt b/CMakeLists.txt
index f3c89f1..4c4239b 100644
--- a/CMakeLists.txt
+++ b/CMakeLists.txt
@@ -185,9 +185,9 @@
 foreach(t ${LLVM_TARGETS_TO_BUILD})
   message(STATUS "Targeting ${t}")
   add_subdirectory(lib/Target/${t})
-  if( EXISTS ${CMAKE_SOURCE_DIR}/lib/Target/${t}/AsmPrinter/CMakeLists.txt )
+  if( EXISTS ${LLVM_MAIN_SRC_DIR}/lib/Target/${t}/AsmPrinter/CMakeLists.txt )
     add_subdirectory(lib/Target/${t}/AsmPrinter)
-  endif( EXISTS ${CMAKE_SOURCE_DIR}/lib/Target/${t}/AsmPrinter/CMakeLists.txt )
+  endif( EXISTS ${LLVM_MAIN_SRC_DIR}/lib/Target/${t}/AsmPrinter/CMakeLists.txt )
 endforeach(t)
 
 add_subdirectory(lib/ExecutionEngine)