Removed the SDL_PATH_DSP environment variable from the NetBSD and OSS audio driver

The AUDIODEV environment variable is no longer used by other audio drivers, and can be used exclusively to specify the DSP audio device.

docs/README-migration.md

@@ -801,6 +801,9 @@ The following hints have been removed:
 * SDL_HINT_XINPUT_USE_OLD_JOYSTICK_MAPPING
 * SDL_HINT_AUDIO_DEVICE_APP_NAME - replaced by either using the appname param to SDL_SetAppMetadata() or setting SDL_PROP_APP_METADATA_NAME_STRING with SDL_SetAppMetadataProperty()
 
+The following environment variables have been renamed:
+* SDL_PATH_DSP => AUDIODEV
+
 The following environment variables have been removed:
 * SDL_AUDIO_ALSA_DEBUG - replaced by setting the hint SDL_HINT_LOGGING to "audio=debug"
 * SDL_DUMMYAUDIODELAY - replaced with the hint SDL_HINT_AUDIO_DUMMY_TIMESCALE which allows scaling the audio time rather than specifying an absolute delay.

src/audio/SDL_audiodev.c

@@ -87,10 +87,7 @@ static void SDL_EnumUnixAudioDevices_Internal(const SDL_bool recording, const SD
     }
 
     // Figure out what our audio device is
-    audiodev = SDL_getenv("SDL_PATH_DSP");
-    if (!audiodev) {
-        audiodev = SDL_getenv("AUDIODEV");
-    }
+    audiodev = SDL_getenv("AUDIODEV");
     if (!audiodev) {
         if (classic) {
             audiodev = SDL_PATH_DEV_AUDIO;