build and run FileUtilTest in CMake builds

Summary:
Remove the `HANGING` tag from this test, so that it is run by default in the
CMake build.

Differential Revision: D21367512

fbshipit-source-id: 4bb707c83005ee8cd39ed2ce6b82b7f0c53f2c88

CMakeLists.txt

@@ -841,8 +841,7 @@ if (BUILD_TESTS)
       TEST file_test SOURCES FileTest.cpp
       # Open-source linux build can't handle running this.
       #TEST file_lock_test SOURCES FileLockTest.cpp
-      TEST file_util_test HANGING
-        SOURCES FileUtilTest.cpp
+      TEST file_util_test SOURCES FileUtilTest.cpp
       TEST fingerprint_test SOURCES FingerprintTest.cpp
       TEST fixed_string_test SOURCES FixedStringTest.cpp
       TEST format_other_test SOURCES FormatOtherTest.cpp