glsl: introduce ir_binop_all_equal and ir_binop_any_equal, allow vector cmps

glsl: introduce ir_binop_all_equal and ir_binop_any_equal, allow vector cmps

Currently GLSL IR forbids any vector comparisons, and defines "ir_binop_equal"
and "ir_binop_nequal" to compare all elements and give a single bool.

This is highly unintuitive and prevents generation of optimal Mesa IR.

Hence, first rename "ir_binop_equal" to "ir_binop_all_equal" and
"ir_binop_nequal" to "ir_binop_any_nequal".

Second, readd "ir_binop_equal" and "ir_binop_nequal" with the same semantics
as less, lequal, etc.

Third, allow all comparisons to acts on vectors.

Signed-off-by: Ian Romanick <ian.d.romanick@intel.com>