Remove samplers from dx9 constant buffers.

They should only appear as resources.
Fix movc with boolean constant as the condition

Seen with ps4\RaycastTerrainShootRayPS test
movc r0.xyz, cb0[0].wwww, r0.xyzx, cb1[11].xzyx
where cb0[0].wwww is a bool type constant.
Previously would generate 4 if-else statements with (illegal) .x, .y. z.
and .w swizzle on the boolean. Now it is just 1 if-else statement with
.x after upcast to vec4.