Always compile the `oss_sample_types` function
Bug: https://bugs.gentoo.org/621758

Also, conditionally use pulseaudio_sample_types:
```
audio.c: In function ‘mus_audio_device_sample_type’:
audio.c:5687:5: error: implicit declaration of function ‘pulseaudio_sample_types’; did you mean ‘alsa_sample_types’? [-Werror=implicit-function-declaration]
 5687 |     pulseaudio_sample_types(dev, mixer_vals);
      |     ^~~~~~~~~~~~~~~~~~~~~~~
      |     alsa_sample_types
```
--- a/audio.c
+++ b/audio.c
@@ -744,7 +744,6 @@ static int oss_mus_audio_open_input(int ur_dev, int srate, int chans, mus_sample
 }
 
 
-#if (!HAVE_ALSA) && (!HAVE_JACK_IN_LINUX)
 static int oss_sample_types(int ur_dev, mus_sample_t *val)
 {
   int fd, samp_types = 0, sys, ind;
@@ -775,7 +774,6 @@ static int oss_sample_types(int ur_dev, mus_sample_t *val)
   val[0] = (mus_sample_t)(ind - 1);
   return(MUS_NO_ERROR);
 }
-#endif



--- a/audio.c
+++ b/audio.c
@@ -5682,7 +5682,7 @@ mus_sample_t mus_audio_device_sample_type(int dev) /* snd-dac */
 #endif
 #endif

-#if defined(MUS_PULSEAUDIO)
+#if defined(MUS_PULSEAUDIO) && (!(defined(AUDIO_OK)))
   if (mixer_vals[0] == MUS_UNKNOWN_SAMPLE)
     pulseaudio_sample_types(dev, mixer_vals);
 #endif
--
2.38.0