i965: Rewrite ir_tex to ir_txl with lod 0 for vertex shaders
i965: Rewrite ir_tex to ir_txl with lod 0 for vertex shaders

The ir_tex opcode turns into a sample or sample_c message, which will try to
compute derivatives to determine the lod. This produces garbage for
non-fragment shaders where the sample coordinates don't correspond to
subspans.

We fix this by rewriting the opcode from ir_tex to ir_txl and setting the
lod to 0.

Bugzilla: https://bugs.freedesktop.org/show_bug.cgi?id=89457
Cc: "10.5" <59f39c0db42d4479a46b02d4d2bc11120e37bb44@lists.freedesktop.org>
Signed-off-by: Kristian Høgsberg <4b441a45a1cdbce08ca0aaabb01d554a77184d64@intel.com>
Reviewed-by: Kenneth Graunke <bd2562f754ec92342f93f61c25d731e290a2ffa8@whitecape.org>
Reviewed-by: Ian Romanick <2b237cafb16dc45038e85df6c85e74e6d899eba9@intel.com>

metora/MesaGLSLCompiler,metora/MesaGLSLCompiler,metora/MesaGLSLCompiler