glsl parser: handle interface block member qualifier

glsl parser: handle interface block member qualifier

An interface block member may specify the type:
in {
    in vec4 in_var_with_qualifier;
};

When specified with the member, it must match the same
type as interface block type.

It can also omit the qualifier:
uniform {
    vec4 uniform_var_without_qualifier;
};

When the type is not specified with the member,
it will adopt the same type as the interface block.

Signed-off-by: Jordan Justen <jordan.l.justen@intel.com>
Reviewed-by: Kenneth Graunke <kenneth@whitecape.org>