glsl: move uniform calculation to link_uniforms

glsl: move uniform calculation to link_uniforms

Patch moves uniform calculation to happen during link_uniforms, this
is possible with help of UniformRemapTable that has all the reserved
locations.

Location assignment for implicit locations is changed so that we
utilize also the 'holes' that explicit uniform location assignment
might have left in UniformRemapTable, this makes it possible to fit
more uniforms as previously we were lazy here and wasting space.

Fixes following CTS tests:
   ES31-CTS.explicit_uniform_location.uniform-loc-mix-with-implicit-max
   ES31-CTS.explicit_uniform_location.uniform-loc-mix-with-implicit-max-array

v2: code cleanups, increment NumUniformRemapTable correctly, fix
    find_empty_block to work properly and add some more comments.

Signed-off-by: Tapani Pälli <tapani.palli@intel.com>
Reviewed-by: Marta Lofstedt <marta.lofstedt@intel.com>