Log Message:
Update to latest bmake which now uses a date based version.
Same for mk-files.  In the case of bmake the version closely
corresponds to the date of the latest sync with usr.bin/make.

Changes to bmake since 3.1.18 include:

	Pick up fixes for const-correctness, now passes WARNS=3 on
	NetBSD.
	Pick up :ts modifier, allows controlling the separator used
	between words in variable expansion.

	* FILES: include boot-strap and os.sh

	* Makefile.in: only set WARNS if we are NetBSD, the effect on
	FreeBSD is known to be bad.

	* makefile.boot.in (bootstrap): make this the default target.

	* Makefile.in: bump version to 3.1.19

	* machine.sh: avoid A-Z with tr as it is bound to lose.

	Pick up fix for PR/19781 - unhelpful error msg on unclosed ${var:foo
	Plus some doc fixes.

Changes to mk-files since 1.3.2:

	Don't inlcue -pipe in CC for SunOS.

	Make it easier to do non-root installs by overriding *_INSTALL_OWN.
	Use STRIP_FLAG rather than STRIP for -s
	Avoid use of A-Z with tr.
	Avoid searching above /a/b/ when looking for
	top-of-tree Linux at least hangs if you try to examine an automount
	mount point.