[ALSA] PCM midlevel & PCM OSS - make procfs & OSS plugin code optional

Modules: ALSA Core,PCM Midlevel,ALSA<-OSS emulation,USB generic driver

1) The verbose procfs code for the PCM midlevel and usb audio
   can be removed now (more patches will follow).
   CONFIG_SND_VERBOSE_PROCFS
2) The PCM OSS plugin system can be also compiled optionaly.
   CONFIG_SND_PCM_OSS_PLUGINS

Signed-off-by: Jaroslav Kysela <perex@suse.cz>

sound/core/oss/pcm_plugin.c

@@ -25,6 +25,9 @@
 #endif
 
 #include <sound/driver.h>
+
+#ifdef CONFIG_SND_PCM_OSS_PLUGINS
+
 #include <linux/slab.h>
 #include <linux/time.h>
 #include <linux/vmalloc.h>
@@ -916,3 +919,5 @@ int snd_pcm_area_copy(const struct snd_pcm_channel_area *src_area, size_t src_of
 	}
 	return 0;
 }
+
+#endif