Reduce the scope of the VM object locking in brelse().  In my tests, this
change reduced the total number of VM object lock acquisitions by brelse()
by 74%.

Sponsored by:	EMC / Isilon Storage Division
Add 'static' where able.
Correct check to see if file changes.

Reported by:	swildner@DragonFlyBSD.org
Reviewed by:	des
Remove unnecessary #include's.
Standardize the way functions build their arguments leading up to a dialog
invocation. Specifically, "top-load" your arguments and in the order in-
which they will be displayed. For example, many [if not all] widgets display
information in the following order, top-to-bottom (visually):

+ backtitle (displayed behind the widget at top-left)
+ title (at the top of the `window')
+ prompt text (just below the title and above whatever widget you choose)
+ Depending on widget, _one_ of the following:
  - menu list
  - radio list
  - check list
  - text input box with initial text
  - [Xdialog(1)] 2x or 3x text input boxes
  - [dialog(1)] a multi-part form
  - progress bar
  - etc. (many more widget choices)
+ buttons (right below the selected widget)
+ [dialog(1)] the hline (displayed at bottom of `window')

NOTE: Xdialog(1) accepts and silently ignores --hline

When building local arguments for your dialog invocation, if the value can't
be cleanly loaded into a local, add "# Calculated below" to the end of the
local declaration while retaining the block order of argument declarations.

Move other local declarations that are not associated with this top-loading
the dialog arguments to right-above where they are first-used.

Also, standardize on the names of the arguments. For example, always use
$prompt (instead of sometimes $msg and sometimes $prompt); use $menu_list
or $shell_list or $radio_list for those respective widgets; ad nauseum.

While we're doing this, flush-out full arguments for many invocations that
were passing NULL strings (making it unapparent if you were staring at this
one invocation what argument that NULL string was supposed to represent).

Last, while we're in startup/rcconf let's remove the unnecessary use of a
GLOBAL (RCCONF_MENU_LIST) for the menu_list.
Fix option processing from the library layer to address unexpected
behavior(s); e.g., `-Xd' versus `-dX' did not produce the same results.

The libraries common.subr and dialog.subr automatically process the
arguments passed to the program and enable/disable functionality without the
need to process the arguments within your program. For example, if "$@"
contains `-d', common.subr will see this and enable debugging regardless of
whether you process "$@" yourself or not (this automatic processing can
easily be disabled for custom scripts that don't want it; see the afore-
mentioned scripts for additional details).

NOTE: common.subr stores a copy of "$@" in $ARGV for convenient (and
repeated) processing by libraries such as dialog.subr which provide such
transparent functionality for the consuming script(s).

However, the libraries don't know if a program wants to accept `extra'
options. Flags are not really a problem, because the library can be
programmed to silently ignore unknown flags. The trouble comes into play
when the program wants to define an option that takes an argument.

For example:

	bsdconfig -D logfile -X

In the above example, the library uses getopts to process $ARGV and if it
doesn't know that `-D' takes an argument, the option processing will
prematurely terminate on `logfile' (this is standard/correct behavior for
getopts but is undesired in our situation where we have partially off-loaded
main argument processing).

The problem is solved by allowing the program to define an extra set of
options to be included in each library's handling of $ARGV. Only options
that require arguments are truly necessary to be pre-specified in this new
manner.
Improvements to whitespace and comments.
Make proper use of locals in f_dialog_init().
Use f_isset() (introduced by r250317) instead of `f_quietly f_getvar ...'.
Standardize NULL initialization to be consistent.
Make some obvious consolidations in local declaration for readability.
Add some additional debugging to the common media library.
Fix a copy/paste error within a comment.
Change the name of a couple of functions in `usermgmt/user_input.subr' to
make their purpose more clear by their names:

	f_dialog_input_change() and
	f_dialog_input_expire()

Are now (respectively):

	f_dialog_input_expire_password() and
	f_dialog_input_expire_account()

Upon revisit to this portion of code, the former names were too confusing.
Fix a bug in which the user's choice to Cancel was not properly recognized.
Fix a bug that would cause a spurious warning to appear to appear in an
edge-case. The case was that you have been through the FTP setup once before
and on the second time through, you cancel at the re-selection of a new FTP
server.

The spurious warning was "device_media: not found" and was caused because
the underlying call to f_device_network_down() did not check to see if the
network device existed before attempting to shut it down.

Add checks to make sure we don't forge ahead unless the device exists.
Fix a bug in which the user's choice to Cancel was not recognized. This was
caused by the standard (and correct) behavior of the shell to discard the
return status of lvalue-operands in a pipe-chain.

The solution is to not pipe the file-acquisition directly into sort(1) but
instead store the output (allowing immediate testing of the return status)
and later sort it.
Fix a typo. In this case, the typo caused the f_noyes() invocation to
display a global instead of the passed-argument; however since the global
always has the same value as the passed argument, it made no difference in
the realtime operation.
Like r250701, introduce another handy function for truncating variables to a
specific byte-length. Works like vsnprintf(3).
Move ppp.8.m4 back to ppp.8 and de-ifdef it.

Requested by: joel

MFC after:	1 week