db/upnp/Discovery: don't copy XML to std::string

src/db/upnp/Device.cxx

@@ -99,12 +99,12 @@ protected:
 	}
 };
 
-UPnPDevice::UPnPDevice(const std::string &url, const std::string &description)
+UPnPDevice::UPnPDevice(const std::string &url, const char *description)
 	:ok(false)
 {
 	UPnPDeviceParser mparser(*this);
 	Error error;
-	if (!mparser.Parse(description.data(), description.length(), true,
+	if (!mparser.Parse(description, strlen(description), true,
 			   error)) {
 		// TODO: pass Error to caller
 		LogError(error);

src/db/upnp/Device.hxx

@@ -82,7 +82,7 @@ public:
 	 * @param url where the description came from
 	 * @param description the xml device description
 	 */
-	UPnPDevice(const std::string &url, const std::string &description);
+	UPnPDevice(const std::string &url, const char *description);
 
 	UPnPDevice() : ok(false) {}
 };

src/db/upnp/Discovery.hxx

@@ -66,7 +66,7 @@ class UPnPDeviceDirectory {
 	class ContentDirectoryDescriptor {
 	public:
 		ContentDirectoryDescriptor(const std::string &url,
-					   const std::string &description,
+					   const char *description,
 					   time_t last, int exp)
 			:device(url, description), last_seen(last), expires(exp+20) {}
 		UPnPDevice device;