add an interface for sound libraries

Groundwork for a more versatile interface for using
sound libraries. A lot of sound libraries work across
multiple platforms.

The current NetHack sound stuff is quite limited.

Binaries can have a variety of window ports linked into
them, and it makes sense to have something similar for
sound.

This tries to set things up in a more soundlib-centric way,
rather than inserting things in a platform-centric way.

It establishes a new top-level directory sound (akin to win
for the window interface routines, or "window-port") where
sound-related additions and sndprocs and support files can be
added and used across platforms.

The default interface is nosound and the 'nosound' interface
is in src/sounds.c

The interface for 'windsound', which contains the same minimal
USER_SOUNDS support using built-in routines that has been in the
windows port for a long time is added to
sound/windsound/windsound.c.

For now, the sound interface support for 'qtsound' has been added
to the existing Qt files win/Qt/qt_bind.h and win/Qt/qt_bind.cpp,
and a note has been placed in sound/qtsound/README.md to avoid
confusion.

New header file added: include/sndprocs.h.

sound/qtsound/README.md

@@ -0,0 +1,3 @@
+19-Jan-2023
+The Qt sound interface is currently housed in win/Qt/qt_bind.h and win/Qt/qt_bind.cpp.
+

sound/windsound/windsound.c

@@ -0,0 +1,71 @@
+/* NetHack 3.7	windsound.c	$NHDT-Date: $  $NHDT-Branch: $NHDT-Revision: $ */
+/* Copyright (c) Michael Allison, 2022                                */
+/* NetHack may be freely redistributed.  See license for details. */
+
+#include "win32api.h"
+#include "hack.h"
+#include <mmsystem.h>
+
+/*
+ * The win32api sound interface
+ *
+ */
+
+#include "win32api.h"
+#include "hack.h"
+
+#ifdef SND_LIB_WINDSOUND
+
+static void windsound_init_nhsound(void);
+static void windsound_exit_nhsound(const char *);
+static void windsound_achievement(schar, schar, int32_t);
+static void windsound_soundeffect(char *, int32_t, int32_t);
+static void windsound_hero_playnotes(int32_t instrument, char *str, int32_t volume);
+static void windsound_play_usersound(char *, int32_t, int32_t);
+
+struct sound_procs windsound_procs = {
+    SOUNDID(windsound),
+    0L,
+    windsound_init_nhsound,
+    windsound_exit_nhsound,
+    windsound_achievement,
+    windsound_soundeffect,
+    windsound_hero_playnotes,
+    windsound_play_usersound,
+};
+
+void
+windsound_init_nhsound(void)
+{
+    /* No steps required */
+}
+
+void
+windsound_exit_nhsound(const char *reason)
+{
+}
+
+void
+windsound_achievement(schar ach1, schar ach2, int32_t repeat)
+{
+}
+
+void
+windsound_soundeffect(char *desc, int32_t seid, int32_t volume)
+{
+}
+
+void
+windsound_hero_playnotes(int32_t instrument, char *str, int32_t volume)
+{
+}
+
+void
+windsound_play_usersound(char *filename, int32_t volume UNUSED, int32_t idx UNUSED)
+{
+    /*    pline("play_usersound: %s (%d).", filename, volume); */
+    (void) sndPlaySound(filename, SND_ASYNC | SND_NODEFAULT);
+}
+
+#endif /* SND_LIB_WINDSOUND */
+