intel/fs: Mark 64-bit values as being contiguous

This isn't often a problem , when we're in a compute shader, we must
push the thread local ID so we decrement the amount of available push
space by 1 and it's no longer even and 64-bit data can, in theory, span
it.  By marking those uniforms contiguous, we ensure that they never get
split in half between push and pull constants.

Reviewed-by: Iago Toral Quiroga <itoral@igalia.com>
Cc: mesa-stable@lists.freedesktop.org
(cherry picked from commit 25f7453c)