~/.config/dwm: Support muting/unmuting audio

.config/dwm/config.h

static const char *volumedowncmd[] = { "amixer", "set", "Master", "5%-", NULL };
static const char *volumeupcmd[] = { "amixer", "set", "Master", "5%+", NULL };
static const char *volumetogglecmd[] = { "amixer", "set", "Master", "toggle", NULL };
static const char *screenlockcmd[] = { "slock", NULL };
	{ 0,                            XF86XK_AudioLowerVolume, spawn, { .v = volumedowncmd } },
	{ 0,                            XF86XK_AudioRaiseVolume, spawn, { .v = volumeupcmd } },
	{ 0,                            XF86XK_AudioMute       , spawn, { .v = volumetogglecmd } },
	{ MODKEY|ShiftMask,             XK_l,      spawn,          { .v = screenlockcmd } },
};