gst-plugins-base: make alsa plug-in configurable

It may be desirable not to use the alsa sink for playback
even though alsa-lib is installed. So make this a configuration
option. This also takes care of selecting the proper options
for alsa-lib
(BR2_PACKAGE_ALSA_LIB_MIXER and BR2_PACKAGE_ALSA_LIB_PCM).

[Peter: fix indentation]
Signed-off-by: Sven Neumann <s.neumann@raumfeld.com>
Signed-off-by: Peter Korsgaard <jacmet@sunsite.dk>

package/multimedia/gst-plugins-base/Config.in

@@ -73,6 +73,12 @@ config BR2_PACKAGE_GST_PLUGINS_BASE_PLUGIN_VOLUME
 
 comment "plugins with external dependencies (there may be more available)"
 
+config BR2_PACKAGE_GST_PLUGINS_BASE_PLUGIN_ALSA
+	bool "alsa (mandatory for audio playback)"
+	select BR2_PACKAGE_ALSA_LIB
+	select BR2_PACKAGE_ALSA_LIB_MIXER
+	select BR2_PACKAGE_ALSA_LIB_PCM
+
 config BR2_PACKAGE_GST_PLUGINS_BASE_PLUGIN_OGG
 	bool "ogg (*.ogg audio/video)"
 	select BR2_PACKAGE_LIBOGG

package/multimedia/gst-plugins-base/gst-plugins-base.mk

@@ -40,8 +40,7 @@ ifeq ($(BR2_PACKAGE_ORC),y)
 GST_PLUGINS_BASE_DEPENDENCIES += orc
 endif
 
-# alsa support needs pcm+mixer support, but configure fails to check for it
-ifeq ($(BR2_PACKAGE_ALSA_LIB)$(BR2_PACKAGE_ALSA_LIB_MIXER)$(BR2_PACKAGE_ALSA_LIB_PCM),yyy)
+ifeq ($(BR2_PACKAGE_GST_PLUGINS_BASE_PLUGIN_ALSA),y)
 GST_PLUGINS_BASE_DEPENDENCIES += alsa-lib
 else
 GST_PLUGINS_BASE_CONF_OPT += --disable-alsa