Jump forward to next live TV segment

If playback is at the end of an earlier program in the live TV chain,
skipping forward jumps to the end of the next program
instead of to the beginning of the next program.
Fixed by restoring two casts that were accidentally removed in
commit 7949b0d.

mythtv/libs/libmythtv/mythplayer.cpp

@@ -1481,8 +1481,8 @@ long long MythPlayer::CalcMaxFFTime(long long ffframes, bool setjump) const
         {
             ret = -1;
             // Number of frames to be skipped is from the end of the current segment
-            auto seconds = secondsFromFloat((m_totalFrames - m_framesPlayed - ffframes)
-                                                          / m_videoFrameRate);
+            int64_t frames = (int64_t)m_totalFrames - (int64_t)m_framesPlayed - ffframes;
+            auto seconds = secondsFromFloat(frames / m_videoFrameRate);
             m_playerCtx->m_tvchain->JumpToNext(true, seconds);
         }
     }