[PATCH] udevd race conditions and performance, assorted cleanups

[PATCH] udevd race conditions and performance, assorted cleanups

This patch covers a number of areas:

1) sysfs.h is fixed up to use the common dbg() macro.  This fixes the
case where DEBUG is defined but USE_LOG isn't.

2) udevstart.c is modified to include the proper headers, rather than
getting them indirectly which can break depending on Makefile flags

3) udevd.c gets some major changes:
a) I added a pipe from the signal handler.  This fixes the race
conditions that I mentioned earlier.  Basically, the point of the pipe
is to force the select() call to return immediately if a signal handler
fired before we actually started the select() call.  This then lets us
run the appropriate code based on flags set in the signal handler proper.
b) I added a number of flags to coalesce calls to common routines.  This
should make things slightly more efficient.
c) since most calls will tend to come in with a sequence number larger
than what has been received, I switched msg_queue_insert() to scan the
msg_list backwards to improve performance.

 filename="udevd.diff"