i965: Replace brw_wm_* with dumping code into the fs_visitor.

i965: Replace brw_wm_* with dumping code into the fs_visitor.

This makes a giant pile of code newly dead.  It also fixes TXB on newer
chipsets, which has been totally broken (I now have a piglit test for that).
It passes the same set of Ian's ARB_fragment_program tests.  It also improves
high-settings ETQW performance by 3.2 +/- 1.9% (n=3), thanks to better
optimization and having 8-wide along with 16-wide shaders.

Bugzilla: https://bugs.freedesktop.org/show_bug.cgi?id=24355
Reviewed-by: Kenneth Graunke <kenneth@whitecape.org>