TableGen uses exceptions, but is not used.

Change-Id: I3a54c2f72784169804b3305c26f17c63c313931e
Reviewed-on: https://swiftshader-review.googlesource.com/9851Reviewed-by: Lingfeng Yang <lfy@google.com>
Reviewed-by: Nicolas Capens <capn@google.com>
Tested-by: Lingfeng Yang <lfy@google.com>