i965/fs: do not depend on std140 alignment rules for UBO loads
i965/fs: do not depend on std140 alignment rules for UBO loads

The previous implementation relied on the std140 alignment rules to
avoid handling misalignment in the case where we are loading more than
2 double components from a vector, which requires to emit a second load
message.

This alternative implementation deals with misalignment and is more
flexible going forward.

Reviewed-by: Iago Toral Quiroga <a847aabaac44184372f6b1cd1a59aa254daaeb0b@igalia.com>

metora/MesaGLSLCompiler,metora/MesaGLSLCompiler,metora/MesaGLSLCompiler