Revert "Remove unnecessary flags in Legion CMake build (#932)"

[manopapad]

This reverts commit 5d74fdc115f6a4b06baa3f145d2a837c24126974.

CI had not actually fully succeeded on #932, rather the bot was waiting for us to tell it "\ok to test" again, and there is no indication that this was required on the test results.

So reverting this, and will reopen it to try and fix the errors.