meta: Use internal functions to set texture parameters

meta: Use internal functions to set texture parameters

_mesa_texture_parameteriv is used because (the more obvious)
_mesa_texture_parameteri just stuffs the parameter in an array and calls
_mesa_texture_parameteriv.  This just cuts out the middleman.

As a side bonus we no longer need check that ARB_stencil_texturing is
supported.  The test doesn't allow non-supporting implementations to
avoid any work, and it's redundant with the value-changed test.

Fix bug #93717 because the state restore commands at the bottom of
_mesa_meta_GenerateMipmap no longer depend on the bound state.

Fixes  piglit   arb_direct_state_access-generatetexturemipmap  with  the
changes  recently sent  to the  piglit mailing  list.  See  the bugzilla
entry for more info.

Signed-off-by: Ian Romanick <ian.d.romanick@intel.com>
Bugzilla: https://bugs.freedesktop.org/show_bug.cgi?id=93717
Cc: "11.0 11.1" <mesa-stable@lists.freedesktop.org>
Reviewed-by: Jason Ekstrand <jason.ekstrand@intel.com>