glsl: always copy bindless sampler packing constructors to a temp

The logic for inlining functions with sampler params is complex and has a number of special cases. This fixes a segfault in the builtin inlining code.

Closes: #11648 (closed) Fixes: 3cdcc5f0 ("glsl: implement ARB_bindless_texture conversions")

Piglit: piglit!939 (merged)