audio/gqmpeg: add sndio volume backend and fixes crashes

This diff makes gqmpeg use sndio to display and control the
volume. This fixes the crash when the volume slider is touched. As a
side effect, this makes gqmpeg use the right device (one that's
playing) and nicely updates the slider position when other programs
change the master volume.

OK?

Index: Makefile
===================================================================
RCS file: /cvs/ports/audio/gqmpeg/Makefile,v
retrieving revision 1.64
diff -u -p -r1.64 Makefile
--- Makefile 12 Jul 2019 20:43:33 -0000 1.64
+++ Makefile 8 Mar 2020 15:39:53 -0000
@@ -3,7 +3,7 @@
COMMENT= front-end to various audio players

DISTNAME= gqmpeg-0.91.1
-REVISION= 14
+REVISION= 15
CATEGORIES= audio

HOMEPAGE= http://gqmpeg.sourceforge.net/
Index: patches/patch-src_Makefile_in
===================================================================
RCS file: patches/patch-src_Makefile_in
diff -N patches/patch-src_Makefile_in
--- /dev/null 1 Jan 1970 00:00:00 -0000
+++ patches/patch-src_Makefile_in 8 Mar 2020 15:39:53 -0000
@@ -0,0 +1,14 @@
+$OpenBSD$
+
+Index: src/Makefile.in
+--- src/Makefile.in.orig
++++ src/Makefile.in
+@@ -342,7 +342,7 @@ gqmpeg_SOURCES = \
+ $(module_mpg123) $(module_xmp) $(module_ogg123) $(module_radio)
+
+
+-gqmpeg_LDADD = $(GTK_LIBS) $(LIBPNG)
++gqmpeg_LDADD = $(GTK_LIBS) $(LIBPNG) -lsndio
+
+ EXTRA_DIST = \
+ $(extra_SLIK) \
Index: patches/patch-src_mixer_c
===================================================================
RCS file: /cvs/ports/audio/gqmpeg/patches/patch-src_mixer_c,v
retrieving revision 1.2
diff -u -p -r1.2 patch-src_mixer_c
--- patches/patch-src_mixer_c 14 Oct 2007 14:12:42 -0000 1.2
+++ patches/patch-src_mixer_c 8 Mar 2020 15:39:53 -0000
@@ -1,39 +1,288 @@
$OpenBSD: patch-src_mixer_c,v 1.2 2007/10/14 14:12:42 jasper Exp $
---- src/mixer.c.orig Tue Sep 10 16:16:26 2002
-+++ src/mixer.c Sun Oct 14 15:47:27 2007
-@@ -285,7 +285,11 @@ void mixer_init(gint init_device_id)
-
- mixer_device = getenv("MIXERDEVICE");
- if (mixer_device == NULL)
-+#ifdef __OpenBSD__
-+ mixer_device = "/dev/mixer";
-+#else
- mixer_device = "/dev/mixer0";
-+