clc: Tell clang to track imported dependencies

This is a rebase of !28348 (closed), changing only the common mesa_clc now that we have that (instead of independent driver clc's -- although Intel still needs to port over to get the benefit). It also fixes the bug in that MR where we'd overwrite dep files when inputting multiple files.

This simplifies our meson rules and, more importantly, eliminates a class of build system fails that will only become more common once we have more common code #included in the CL world.