Merge branch 'outputswritten64'

Merge branch 'outputswritten64'

Add a GLbitfield64 type and several macros to operate on 64-bit
fields.  The OutputsWritten field of gl_program is changed to use that
type.  This results in a fair amount of fallout in drivers that use
programs.

No changes are strictly necessary at this point as all bits used are
below the 32-bit boundary.  Fairly soon several bits will be added for
clip distances written by a vertex shader.  This will cause several
bits used for varyings to be pushed above the 32-bit boundary.  This
will affect any drivers that support GLSL.

At this point, only the i965 driver has been modified to support this
eventuality.

I did this as a "squash" merge.  There were several places through the
outputswritten64 branch where things were broken.  I foresee this
causing difficulties later for bisecting.  The history is still
available in the branch.

Conflicts:
	src/mesa/drivers/dri/i965/brw_wm.h