Ugh, fix CMake.

git-svn-id: https://llvm.org/svn/llvm-project/cfe/trunk@134848 91177308-0d34-0410-b5e6-96231b3b80d8
diff --git a/tools/c-arcmt-test/CMakeLists.txt b/tools/c-arcmt-test/CMakeLists.txt
index bcb963d..351f4ad 100644
--- a/tools/c-arcmt-test/CMakeLists.txt
+++ b/tools/c-arcmt-test/CMakeLists.txt
@@ -6,7 +6,7 @@
   )
 
 add_clang_executable(c-arcmt-test
-  c-arcmt-test.cpp
+  c-arcmt-test.c
   )
 
 set_target_properties(c-arcmt-test