bug#24919: 24.5; battery.el not working in FreeBSD

[Ignacio Torres]

Running M-x battery in FreeBSD returns:

Power disconnected, battery high (illegal% load, remaining time 0:00)

The battery-bsd-apm function was contributed in [1]. It contains:

(apm-cmd (concat "/usr/sbin/apm -ablm" apm-flag))

The -m flag used in NetBSD[2] and OpenBSD[3] to show the remaining time
in minutes does not exist in FreeBSD[4]. Instead -t should be used to
show the remaining time in seconds.

Also the resulting output is in a different order than that expected by
the parser. battery-bsd-apm expects the order to be:

battery-status
battery-percentage
battery-life
line-status
apm-mode

In FreeBSD it is:

line-status
battery-status
battery-percentage
apm-mode
battery-life

As can be seen in the source of /usr/sbin/apm.c[5]

[1] 
http://git.savannah.gnu.org/cgit/emacs.git/commit/lisp/battery.el?id=19b748ad448c37d08ae1df1212aec22ee1d55956
[2] http://netbsd.gw.com/cgi-bin/man-cgi?apm++NetBSD-current
[3] http://man.openbsd.org/OpenBSD-current/man8/amd64/apm.8
[4] 
https://www.freebsd.org/cgi/man.cgi?query=apm&manpath=FreeBSD+10.3-RELEASE+and+Ports
[5] 
https://svnweb.freebsd.org/base/stable/11/usr.sbin/apm/apm.c?revision=302408&view=markup#l472



In GNU Emacs 24.5.1 (amd64-portbld-freebsd12.0, GTK+ Version 2.24.29)
 of 2016-08-27 on builds.trueos.org
Windowing system distributor `The X.Org Foundation', version 11.0.11804000
Configured using:
 `configure --localstatedir=/var --disable-acl --with-dbus
 --without-file-notification --with-gconf --with-gif --with-gnutls
 --with-gsettings --with-jpeg --with-m17n-flt --with-imagemagick
 --with-libotf --with-png --with-toolkit-scroll-bars --with-rsvg
 --with-tiff --with-x --with-xft --with-xim --with-xml2 --with-xpm
 --with-x-toolkit=gtk2 --with-sound=oss --x-libraries=/usr/local/lib
 --x-includes=/usr/local/include --prefix=/usr/local
 --mandir=/usr/local/man --infodir=/usr/local/share/emacs/info/
 --build=amd64-portbld-freebsd12.0 'CFLAGS=-O2 -pipe -isystem
 /usr/local/include -fstack-protector -fno-strict-aliasing'
 'CPPFLAGS=-isystem /usr/local/include' 'LDFLAGS= -L/usr/local/lib
 -Wl,-rpath=/usr/lib:/usr/local/lib -fstack-protector''

Important settings:
  value of $LC_ALL: en_US.UTF-8
  value of $LANG: en_US.UTF-8
  locale-coding-system: utf-8-unix