dvb.media_addon: Trigger loading of media plugins.

- This is the workaround as described in the bug report #11018.
- I would have preferred to place this workaround in DVBMediaAddon::InitCheck()
  as this method can return a status code but unfortunately it is never called.

src/add-ons/media/media-add-ons/dvb/DVBMediaAddon.cpp

@@ -55,6 +55,20 @@ make_media_addon(image_id id)
 DVBMediaAddon::DVBMediaAddon(image_id id)
  :	BMediaAddOn(id)
 {
+	// TODO: The following code block is a workaround for the bug #11018
+	// (https://dev.haiku-os.org/ticket/11018). Please remove this code block,
+	// once the bug is being resolved.
+	// The workaround triggers the loading of all media plugins prior to using
+	// methods of class BMediaFormats. Using the function get_next_encoder()
+	// is used because of two facts
+	//     1. It is publicly available and thus can be used by 3rd party apps,
+	//        too.
+	//     2. It is already available by including BMediaFormats.h, so there is
+	//        no need to include another header for this workaround.
+	int32 workaroundCookie = 0;
+	media_codec_info workaroundMediaCodecInfo;
+	get_next_encoder(&workaroundCookie, &workaroundMediaCodecInfo);
+
 	ScanFolder("/dev/dvb");
 }
 
@@ -68,10 +82,12 @@ DVBMediaAddon::~DVBMediaAddon()
 status_t
 DVBMediaAddon::InitCheck(const char ** out_failure_text)
 {
+	debugger("");
 	if (!fDeviceList.CountItems()) {
 		*out_failure_text = "No supported device found";
 		return B_ERROR;
 	}
+
 	return B_OK;
 }