Enable nomatch events when one_nomatch is empty

[iciliaat_gmail.com]

Summary

To avoid redundant nomatch events on boot, a new sysctl is introduced, which is set to 0 initially. This blocks nomatch events within devctl_nomatch_handler in /sys/kern/devctl.c. When $one_nomatch in /etc/rc.d/devmatch is empty, the value of the sysctl is set to 1, allowing nomatch events to be processed.

[cperciva]

Minor nits.

libexec/rc/rc.d/devmatch

49

The -w option is not needed (and does nothing on FreeBSD).

sys/kern/kern_devctl.c

93

Please wrap this at 78 columns, with a 4-space indent on the second line (like the hw.bus.devctl_queue declaration is formatted).

214–215

The == 1 is not needed, just make this if (nomatch_enabled).

217

No need for the else return, we're doing that anyway. ;-)

[iciliaat_gmail.com]

Fixed formatting, and unneccessary parts

[iciliaat_gmail.com]

Updated commit message to include boot speed improvement

[cperciva]

Add Warner as a reviewer in case he has any comments on this before I commit it.