blitter: don't over-cache shader
fs_texfetch_col_swizzle is parameterized on the number of samples and whether or not it needs to handle swizzle. Make sure that the cached shader is recreated if the parameters change.
fs_texfetch_col_swizzle is parameterized on the number of samples and whether or not it needs to handle swizzle. Make sure that the cached shader is recreated if the parameters change.