mkvparser: fix float conversion warning

Change-Id: I2b79a6af431f9c51e5c32c75da18645674ebbb4d
diff --git a/mkvparser/mkvparser.cc b/mkvparser/mkvparser.cc
index a3995de..c96d263 100644
--- a/mkvparser/mkvparser.cc
+++ b/mkvparser/mkvparser.cc
@@ -4032,7 +4032,7 @@
   }
 
   const double rollover_check = m_duration * m_timecodeScale;
-  if (rollover_check > LLONG_MAX)
+  if (rollover_check > static_cast<double>(LLONG_MAX))
     return E_FILE_FORMAT_INVALID;
 
   if (pos != stop)