i965: Save meta stencil blit programs in the context.

i965: Save meta stencil blit programs in the context.

When the last context in a share group is destroyed, the hash table
containing all of the shader programs (ctx->Shared->ShaderObjects) is
destroyed, throwing away all of the shader programs.

Using a static variable to store program IDs ends up holding on to them
after this, so we think we still have a compiled program, when it
actually got destroyed.  _mesa_UseProgram then hits GL errors, since no
program by that ID exists.

Instead, store the program IDs in the context, so we know to recompile
if our context gets destroyed and the application creates another one.

Fixes es3conform tests when run without -minfmt (where it creates
separate contexts for testing each visual).

Bugzilla: https://bugs.freedesktop.org/show_bug.cgi?id=77865
Signed-off-by: Kenneth Graunke <kenneth@whitecape.org>
Reviewed-by: Eric Anholt <eric@anholt.net>
Reviewed-by: Ian Romanick <ian.d.romanick@intel.com>
Cc: "10.2" <mesa-stable@lists.freedesktop.org>