st/glsl_to_tgsi: make samplers_used an uint32_t (v2)
st/glsl_to_tgsi: make samplers_used an uint32_t (v2)

It is used as a bitfield, so it seems cleaner to keep it unsigned.

The literal 1 is a (signed) int, and shifting into the sign bit is undefined
in C, so change occurences of 1 to 1u.

v2: add an assert for bitfield size and use 1u << idx

Reviewed-by: Brian Paul <3cb4e1df5ec4da2c7c4af7c52cec8cf340a55a10@vmware.com>
Reviewed-by: Roland Scheidegger <7d58aee419d6f9201d75517c885374dff5e7d848@vmware.com> (v1)
Reviewed-by: Marek Olšák <8c7344a1abdb103e79ecfd488098373070c3c70e@amd.com> (v1)

metora/MesaGLSLCompiler,metora/MesaGLSLCompiler,metora/MesaGLSLCompiler