tgsi: handle projection modifier for array textures.

tgsi: handle projection modifier for array textures.

This partly reverts 6ace2e41da7dded630d932d03bacb7e14a93d47a.
Apparently with GL_MESA_texture_array fixed-function texturing
with texture arrays is possible, and hence we have to handle TXP.
(Though noone seems to know the semantics, softpipe now does what
it did before, which is to NOT project the array coord, llvmpipe
for instance however indeed does project the array coord. Unlike
before it will project the comparison coord for shadow1d array, as
that clearly was an error.)
This fixes https://bugs.freedesktop.org/show_bug.cgi?id=61828.

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