Add SRC_UPDATE_SKIP, DOC_UPDATE_SKIP, and PORTS_UPDATE_SKIP

variables.  These are intended to allow bypassing the
'svn co /usr/{src,doc,ports}' step in the chroot when the
tree exists from external means.

The use case here is that /usr/src, /usr/doc, and /usr/ports
in the chroot exist as result of zfs dataset clones, so it
is possible (and happens quite often) that the included
distributions may not be consistent.  (This is not the case
for -RELEASE builds, but does happen for snapshot builds.)

Tested on:	stable/9@r264319
MFC After:	3 days
Sponsored by:	The FreeBSD Foundation

1 files changed, 25 insertions, 1 deletions

diff --git a/share/man/man7/release.7 b/share/man/man7/release.7
index 1278a62..f3f897e 100644
--- a/share/man/man7/release.7
+++ b/share/man/man7/release.7
@@ -24,7 +24,7 @@
 .\"
 .\" $FreeBSD$
 .\"
-.Dd April 2, 2014
+.Dd April 11, 2014
 .Dt RELEASE 7
 .Os
 .Sh NAME
@@ -272,6 +272,30 @@ build environment setup are skipped.
 This is intended solely for cases where the
 .Xr chroot 8
 userland are provided by alternate means.
+.It Va SRC_UPDATE_SKIP
+Set to a non-empty value to prevent checkout or update of
+.Fa /usr/src
+within the
+.Xr chroot 8 .
+This is intended for use only when
+.Fa /usr/src
+is expected to exist by alternative means.
+.It Va DOC_UPDATE_SKIP
+Set to a non-empty value to prevent checkout or update of
+.Fa /usr/doc
+within the
+.Xr chroot 8 .
+This is intended for use only when
+.Fa /usr/doc
+is expected to exist by alternative means.
+.It Va PORTS_UPDATE_SKIP
+Set to a non-empty value to prevent checkout or update of
+.Fa /usr/ports
+within the
+.Xr chroot 8 .
+This is intended for use only when
+.Fa /usr/ports
+is expected to exist by alternative means.
 .El
 .Sh EMBEDDED BUILDS
 The following