lib/alsa/Format: move HAVE_ALSA_DSD* definitions from the Alsa output plugin

src/lib/alsa/Format.hxx

@@ -28,6 +28,16 @@
 
 #include <assert.h>
 
+#if SND_LIB_VERSION >= 0x1001c
+/* alsa-lib supports DSD since version 1.0.27.1 */
+#define HAVE_ALSA_DSD
+#endif
+
+#if SND_LIB_VERSION >= 0x1001d
+/* alsa-lib supports DSD_U32 since version 1.0.29 */
+#define HAVE_ALSA_DSD_U32
+#endif
+
 /**
  * Convert MPD's #SampleFormat enum to libasound's snd_pcm_format_t
  * enum.  Returns SND_PCM_FORMAT_UNKNOWN if there is no according ALSA

src/output/plugins/AlsaOutputPlugin.cxx

@@ -44,16 +44,6 @@
 
 #include <string>
 
-#if SND_LIB_VERSION >= 0x1001c
-/* alsa-lib supports DSD since version 1.0.27.1 */
-#define HAVE_ALSA_DSD
-#endif
-
-#if SND_LIB_VERSION >= 0x1001d
-/* alsa-lib supports DSD_U32 since version 1.0.29 */
-#define HAVE_ALSA_DSD_U32
-#endif
-
 static const char default_device[] = "default";
 
 static constexpr unsigned MPD_ALSA_BUFFER_TIME_US = 500000;