Imagine large number of similar computers (for example border
routers of company branches, workstations within computer lab or so). The
compile options used during 'buildworld' are identical for all computers
within such group. When SA issued and OS patched, we should update source
tree on all machines then 'buildworld'/'installworld'. It's time expensive.

	The other way is 'buildworld' on the selected machine, export
/usr/src & /usr/obj via NFS, mount'em on other computers then do
'installworld'.

	The standard install transfer every file despite only few files has
been changed (assuming use of -DNOCLEAN during 'buildworld'). 

	Unnecesarry transfers of large amount of data may disturb during updates of
remote computers connected via slow links. Even on fast network the reading
of large amount of data can be time consuming.

	-C option of current 'install' didn't help - the source file is transfered
during comparsion.

	I would like to suggest to create option '-q' (quick) which allow user to modify
the comparsion alghoritm. It skip comparsion of content of files but use
modification time of files instead.

	It may substantially reduce the amount of transferred data and
transfer time during such update.

	It's usefull when mtime on destination files follows the mtime on
sources only - so '-q' imply '-p' ('-p' imply '-C' already).

Fix: I suggest to add '-q' option modifying compare alghoritm when used. The
most changes are related to compare(). The 'struct stat' of both files are
passed to it so mtimes are avaiable to function if necesarry (current code
pass st_size only to it).

	The patch of manual page should be reviewed by someone who speak
english better than me.
How-To-Repeat: 	N/A