common/descriptor: more aggressive inlining.
common/descriptor: more aggressive inlining.

Once again, GCC at -Os won't inline any but the most trivial of
functions, even when doing so brings a large code size benefit (it's
hard for GCC to see that).

This makes descriptor options significantly cheaper and saves 40 bytes
of ROM to boot.

cbiffle/brittle-kernel,cbiffle/brittle-kernel,cbiffle/brittle-kernel,cbiffle/brittle-kernel