Make test(1) a builtin command of our sh(1) for efficiency. The

Make test(1) a builtin command of our sh(1) for efficiency.  The
binary size increase is 3,784 bytes (about 0.6%).

I don't drop the printf builtin while I'm here because some /etc/rc.*
scripts seem to use it before mounting /usr where printf(1) resides.

Reviewed by:	arch (sheldonh)
Inspired by:	NetBSD, ksh
Clued by:	ume (on how the printf builtin is used)