Prevent firefox from making noise

[Swift Griggs <swiftgriggs%gmail.com@localhost>]

First of all, I love pkgsrc, and give hella credit to the team.  Let's just
get that straight before I start whining about what are possibly my own
self-inflicted problems.

Can one disable or prevent sound from playing from one specific application
(at the OS level)?  If not, then is there any way to simply prevent Firefox
from having sound abilities?  

I notice options to disable PulseAudio (the dirty turd that it is), but I'm
not sure that's going to help if it simply switches to OSS, and Firefox has
been utterly broken in pkgsrc-2015Q4 for me on every system I try to compile
it on for some time now (posted about that about two weeks ago on
pkgsrc-users with no replies).  So, I can't test that theory.  I'm using
Firefox24 since it still works.  Perhaps I've just horked up my systems and
everyone else is fine?

I have zero reason to use Firefox or anything it would spawn to play audio. 
If I want to watch a Youtube video, I use youtube-dl.  If I want to stream
music, I'll use a real streaming utility like mplayer.  I'm one of those
curmudgeons that doesn't like s*** just playing willy-nilly from my infernal
browser.  I flat out just don't want Firefox _touching_ my sound device. 
The reason being that it (and/or flash) rarely releases it in a timely or
easy fashion afterward.  The same goes for flash or nspluginwrapper or some
bit of that Rube-Goldberg machine. I find that I also get into a situation
where after Firefox horks up my sound device I can never get it to function
again without a reboot (and yes, I've used fuser and lsof to look for open
file pointers on every damn sound device - fail: they don't exist). 

Has anyone already solved this ? Does anyone else get a big nasty compile
failure when trying to build pkgsrc/www/firefox out of pkgsrc-2015Q4 ? 

If it's working for folks, then why is it missing from pkg_summary.bz2 and
thus I can't even snag it with pkgin from
ftp://ftp.netbsd.org/pub/pkgsrc/packages/NetBSD/i386/7.0_2015Q4/All ?


Any help / answers would be appreciated. 

-Swift