reapply r198858: Disable LeakSanitizer in TableGen binaries, see PR18325; this time LeakSanitizerIsTurnedOffForTheCurrentProcess is used instead of __lsan_is_turned_off

git-svn-id: https://llvm.org/svn/llvm-project/cfe/trunk@198922 91177308-0d34-0410-b5e6-96231b3b80d8