FrameDump: Set first_frame if movie frame number <= 1

The frame number is incremented before the first frame is swapped out.

Fixes ffmpeg creating invalid video files on output if the emulator only
runs for a single frame, e.g. FifoCI.

Source/Core/VideoCommon/FrameDump.cpp

@@ -443,7 +443,7 @@ FrameDump::Frame FrameDump::FetchState(u64 ticks)
 {
   Frame state;
   state.ticks = ticks;
-  state.first_frame = Movie::GetCurrentFrame() < 1;
+  state.first_frame = Movie::GetCurrentFrame() <= 1;
   state.ticks_per_second = SystemTimers::GetTicksPerSecond();
   state.savestate_index = s_savestate_index;
   return state;