glsl: don't skip GLSL IR opts on first-time compiles

glsl: don't skip GLSL IR opts on first-time compiles

This basically reverts c2bc0aa7b188.

By running the opts we reduce  memory using in Team Fortress 2
from 1.5GB -> 1.3GB from start-up to game menu.

This will likely increase Deus Ex start up times as per commit
c2bc0aa7b188. However currently 32bit games like Team Fortress 2
can run out of memory on low memory systems, so that seems more
important.

Reviewed-by: Marek Olšák <marek.olsak@amd.com>