Rename the VMCore unittest tree to IR. Somehow was missed when doing the
library rename.

llvm-svn: 171747
diff --git a/llvm/unittests/CMakeLists.txt b/llvm/unittests/CMakeLists.txt
index e2b7563..a3f8bf3 100644
--- a/llvm/unittests/CMakeLists.txt
+++ b/llvm/unittests/CMakeLists.txt
@@ -12,4 +12,4 @@
 add_subdirectory(Option)
 add_subdirectory(Support)
 add_subdirectory(Transforms)
-add_subdirectory(VMCore)
+add_subdirectory(IR)