fill_fragment_interpolants() used to have its own logic to find
interpolants, but the context also had
num_interps member, which is
determined with a different logic. In particular,
does not emit interpolants when GL ES is being used and there is
no available color in bits, resulting in smaller
To eliminate the possibility of this kind of inconsistency, replace
interp_input_mask, which is a bitmask of the inputs.
fill_fragment_interpolants() can later query the member to find
interpolants actually created.
num_interps used to track the outputs as
well, but we do not need another bitmask for the outputs because nobody
is currently interested in that.
Signed-off-by: Akihiko Odaki <firstname.lastname@example.org>