glsl: Add ir node for barrier
glsl: Add builtin barrier() function
i965: Add stub for HS barrier() handling

Signed-off-by: Chris Forbes <chrisf@ijw.co.nz>
dont strip a level of arrayness from patch varyings
mesa: Add support for UNIFORM_BLOCK_REFERENCED_BY_TESS_*_SHADER

Signed-off-by: Chris Forbes <chrisf@ijw.co.nz>
mesa: Support querying atomic counters referenced by tess stages

Signed-off-by: Chris Forbes <chrisf@ijw.co.nz>
glsl: Validate restrictions on use of barrier()

With the exception of always-taken switch cases (which are
indistinguishable from straight line code in our IR), this
disallows use of the builtin barrier() function in all the
places it may not appear.

Signed-off-by: Chris Forbes <chrisf@ijw.co.nz>