mesa: Track fixed-function fragment shader as a shader

mesa: Track fixed-function fragment shader as a shader

Previously the fixed-function fragment shader was tracked as a
gl_program.  This means that it shows up in the driver as a Mesa IR
program instead of as a GLSL IR program.  If a driver doesn't generate
Mesa IR from the GLSL IR, that program is empty.  If the program is
empty there is either no rendering or a GPU hang.

Signed-off-by: Ian Romanick <ian.d.romanick@intel.com>
Reviewed-by: Eric Anholt <eric@anholt.net>
Acked-by: Kenneth Graunke <kenneth@whitecape.org>