Fix use of QString::QString.asprintf()

asprintf is a static method and does not modify the calling object.
This fix assigns the returned QString to the calling object.

Fixes issue #10450

src/Vehicle/MAVLinkLogManager.cc

@@ -150,7 +150,7 @@ MAVLinkLogProcessor::valid()
 bool
 MAVLinkLogProcessor::create(MAVLinkLogManager* manager, const QString path, uint8_t id)
 {
-    _fileName.asprintf("%s/%03d-%s%s",
+    _fileName = _fileName.asprintf("%s/%03d-%s%s",
                       path.toLatin1().data(),
                       id,
                       QDateTime::currentDateTime().toString("yyyy-MM-dd-hh-mm-ss-zzz").toLocal8Bit().data(),

src/Vehicle/Vehicle.cc

@@ -1331,7 +1331,7 @@ QString Vehicle::vehicleUIDStr()
 {
     QString uid;
     uint8_t* pUid = (uint8_t*)(void*)&_uid;
-    uid.asprintf("%02X:%02X:%02X:%02X:%02X:%02X:%02X:%02X",
+    uid = uid.asprintf("%02X:%02X:%02X:%02X:%02X:%02X:%02X:%02X",
                  pUid[0] & 0xff,
             pUid[1] & 0xff,
             pUid[2] & 0xff,