Engine reads it out as 64-bit, write it as 64-bit.

Used for bloom luminance.

Material V12's output data was incorrect after the change in d7842d0. Revert this for now (it is currently also unknown whether V12 has 4 or 8 samplers, but only 4 are ever filled on all observed materials so reverting to that, as V12 also uses 4 blend states instead of 8 like V15 does, so its very likely it also only has 4 samplers).