output: const plugin structures

Since the plugin struct is never modified, we should store it in
constant locations.

src/audioOutputs/audioOutput_alsa.c

@@ -413,7 +413,7 @@ static int alsa_playAudio(struct audio_output *audioOutput,
 	return 0;
 }
 
-struct audio_output_plugin alsaPlugin = {
+const struct audio_output_plugin alsaPlugin = {
 	"alsa",
 	alsa_testDefault,
 	alsa_initDriver,

src/audioOutputs/audioOutput_ao.c

@@ -242,7 +242,7 @@ static int audioOutputAo_play(struct audio_output *audioOutput,
 	return 0;
 }
 
-struct audio_output_plugin aoPlugin = {
+const struct audio_output_plugin aoPlugin = {
 	"ao",
 	NULL,
 	audioOutputAo_initDriver,

src/audioOutputs/audioOutput_fifo.c

@@ -272,7 +272,7 @@ static int fifo_playAudio(struct audio_output *audioOutput,
 	return 0;
 }
 
-struct audio_output_plugin fifoPlugin = {
+const struct audio_output_plugin fifoPlugin = {
 	"fifo",
 	NULL, /* testDefaultDeviceFunc */
 	fifo_initDriver,

src/audioOutputs/audioOutput_jack.c

@@ -430,7 +430,7 @@ static int jack_playAudio(struct audio_output *audioOutput,
 	return 0;
 }
 
-struct audio_output_plugin jackPlugin = {
+const struct audio_output_plugin jackPlugin = {
 	"jack",
 	jack_testDefault,
 	jack_initDriver,

src/audioOutputs/audioOutput_mvp.c

@@ -257,7 +257,7 @@ static int mvp_playAudio(struct audio_output *audioOutput,
 	return 0;
 }
 
-struct audio_output_plugin mvpPlugin = {
+const struct audio_output_plugin mvpPlugin = {
 	"mvp",
 	mvp_testDefault,
 	mvp_initDriver,

src/audioOutputs/audioOutput_null.c

@@ -63,7 +63,7 @@ static void null_dropBufferedAudio(struct audio_output *audioOutput)
 	timer_reset(audioOutput->data);
 }
 
-struct audio_output_plugin nullPlugin = {
+const struct audio_output_plugin nullPlugin = {
 	"null",
 	NULL,
 	null_initDriver,

src/audioOutputs/audioOutput_oss.c

@@ -549,7 +549,7 @@ static int oss_playAudio(struct audio_output *audioOutput,
 	return 0;
 }
 
-struct audio_output_plugin ossPlugin = {
+const struct audio_output_plugin ossPlugin = {
 	"oss",
 	oss_testDefault,
 	oss_initDriver,

src/audioOutputs/audioOutput_osx.c

@@ -355,7 +355,7 @@ static int osx_play(struct audio_output *audioOutput,
 	return 0;
 }
 
-struct audio_output_plugin osxPlugin = {
+const struct audio_output_plugin osxPlugin = {
 	"osx",
 	osx_testDefault,
 	osx_initDriver,

src/audioOutputs/audioOutput_pulse.c

@@ -200,7 +200,7 @@ static int pulse_playAudio(struct audio_output *audioOutput,
 	return 0;
 }
 
-struct audio_output_plugin pulsePlugin = {
+const struct audio_output_plugin pulsePlugin = {
 	"pulse",
 	pulse_testDefault,
 	pulse_initDriver,

src/audioOutputs/audioOutput_shout.c

@@ -680,7 +680,7 @@ static void myShout_setTag(struct audio_output *audioOutput,
 	sd->tagToSend = 1;
 }
 
-struct audio_output_plugin shoutPlugin = {
+const struct audio_output_plugin shoutPlugin = {
 	"shout",
 	NULL,
 	myShout_initDriver,

src/output_api.h

@@ -28,7 +28,7 @@
 #include "log.h"
 #include "os_compat.h"
 
-#define DISABLED_AUDIO_OUTPUT_PLUGIN(plugin) struct audio_output_plugin plugin;
+#define DISABLED_AUDIO_OUTPUT_PLUGIN(plugin) const struct audio_output_plugin plugin;
 
 struct audio_output;