Remove a workaround that should be unneeded after r202806.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@332278 91177308-0d34-0410-b5e6-96231b3b80d8
diff --git a/unittests/IR/CMakeLists.txt b/unittests/IR/CMakeLists.txt
index b2782a9..b04b097 100644
--- a/unittests/IR/CMakeLists.txt
+++ b/unittests/IR/CMakeLists.txt
@@ -41,12 +41,6 @@
   WaymarkTest.cpp
   )
 
-# HACK: Declare a couple of source files as optionally compiled to satisfy the
-# missing-file-checker in LLVM's weird CMake build.
-set(LLVM_OPTIONAL_SOURCES
-  ValueMapTest.cpp
-  )
-
 add_llvm_unittest(IRTests
   ${IRSources}
   )