i965: Avoid recompiles for fragment clamping on non-clamping APIs.

i965: Avoid recompiles for fragment clamping on non-clamping APIs.

Removes 75/78 state-dependent recompiles in GLB2.7 (the remaining 3 are
due to FBO-rendering size predictions).  We currently expose
GL_ARB_color_buffer_float on GL core, so we may mis-predict there, but I'm
about to send a patch for removing that silly extension in that case.

Reviewed-by: Jordan Justen <jordan.l.justen@intel.com>
Reviewed-by: Kenneth Graunke <kenneth@whitecape.org>