draw/llvm: Add additional llvm optimization passes

draw/llvm: Add additional llvm optimization passes

It helps a bit with vertex shader performance on i915g
(a couple percent faster with openarena).

I have tried most other passes, and they weren't showing
any measurable improvement. Note that my vertex shaders
didn't have loops, so maybe the loop optimizations could
still be useful in the future.

Reviewed-by: Brian Paul <brianp@vmware.com>