debug: use a Level argument when we can.
debug: use a Level argument when we can.

This change should considerably diminish the use of the Level stack.
The goal, eventually, is to avoid using coroutine-local-storage.

	* include/libport/debug.hh: Rewrite several macros to use the
	version of debug() with explicit level.

aldebaran/libport,aldebaran/libport,aldebaran/libport,aldebaran/libport,aldebaran/libport