Add support for "freebsd-update -r newrelease upgrade" -- binary

upgrading to new releases.  Important parts of this code include
 * automatically determining which optional components (e.g., src,
info, proflibs) are installed.
 * merging changes in files which are modified locally and have
changed between the currently running and new release.
 * prompting the user to rebuild all 3rd party software before
deleting old shared libraries.

Yes, this is compatible with "freebsd-update rollback" -- you can
test a new -BETA and roll back to the old release if you don't
like it.

Subject to re@ approval, this will be MFCed before 7.0-BETA3 and
6.3-RC1.

MFC after:	2 days

1 files changed, 27 insertions, 1 deletions

diff --git a/share/man/man5/freebsd-update.conf.5 b/share/man/man5/freebsd-update.conf.5
index b5352c5..52b16fa 100644
--- a/share/man/man5/freebsd-update.conf.5
+++ b/share/man/man5/freebsd-update.conf.5
@@ -93,7 +93,15 @@ accumulate.
 The parameters following this keyword are regular expressions;
 updates to paths which start with a string matching one of
 these regular expressions will be ignored if the files have
-been modified locally.
+been modified locally (unless they are merged -- see MergeChanges
+below).
+.Pp
+This option can be specified multiple times, and the parameters
+accumulate.
+.It Cm MergeChanges
+The parameters following this keyword are regular expressions;
+updates to paths which start with a string matching one of
+these regular expressions will be merged with local modifications.
 .Pp
 This option can be specified multiple times, and the parameters
 accumulate.
@@ -138,6 +146,24 @@ and specifies whether
 .Cm freebsd-update
 should keep existing file ownership, permissions, and flags
 when installing updates if these have been modified locally.
+.It Cm StrictComponents
+The single parameter following this keyword must be
+.Dq yes
+or
+.Dq no
+and specifies whether
+.Cm freebsd-update
+should interpret the list of components of
+.Fx
+specified via the
+.Cm Components
+option strictly as a list of components installed which
+should be upgraded when the
+.Cm upgrade
+command is used ("yes"), or merely as a list of components
+which might be installed, of which
+.Cm freebsd-update
+should identify which in fact are present ("no").
 .El
 .Sh FILES
 .Bl -tag -width "/etc/freebsd-update.conf"