glsl: fix error message for redeclaring gl_PerVertex as output
mapi: Add ARB_tessellation_shader

V2 [Chris]: Remove display list support; we will only do tessellation
shders in the core profile.
mesa/main: Add ARB_tessellation_shader to extension table.
mesa/main: Add tessellation shader structs
mesa: Add tessellation shader enums

V2 [Chris]: Adjust meta.c as well to avoid undefined behavior.
mesa/main: Add tessellation shader state and limits
mesa/program: Add tessellation shader init functions.

V2 [Chris]: Fix rebase issues; helper previously used here no longer
exists.

Signed-off-by: Chris Forbes <chrisf@ijw.co.nz>
mesa/main: Allow drawing of patch primitives.
mesa/main: tessellation shader / seperate shader objects interaction WIP
mesa: Add tessellation shader builtin varyings.
mesa/main: Allow setting of patch parameters.
mesa/main: Add tessellation shader getters.
mesa/main: Add misc tessellation shader stuff.
mesa/program: Add misc tessellation shader support.
vbo: Add patch size to primitive structure.
glsl: Add tessellation shader defines and built-in variables.
glsl: Add tessellation shader parsing support.
glsl: Allow linking of tessellation shaders.
glsl: Make lower_clip_distance work with tessellation shaders.
glsl: Lower gl_TessLevel* from float[n] to vecn.

Similar to gl_ClipDistance -> gl_ClipDistanceMESA

V2 [Chris]: Fix rebase issues.