Scrcpy: Show FPS directly on screen

[singleNeuron]

Thanks for you work, but could you please show the FPS on the screen instead of stdout.
My English is poor, please don't mind.

[rom1v]

Yes, this would be better, but requires some work.

Firstly, the dependency SDL_ttf must be added to be able to draw text. This would allow to write an OSD component, which could be used to print various messages.

Then, we need to refresh (compute+render) the FPS between frames. Frames are sent only when the device surface content changes, so there may be seconds or minutes without any screen refresh. The FPS should be updated in that case.

_By the way (just a side note), the FPS is just a hint to get an idea of the performance, but it may be misleading: if you watch a 25 FPS fullscreen video, then FPS will be 25, no more, which is perfect. On the other hand, if the encoding/decoding/rendering is not fast enough, the FPS can be 55 while the screen renders at 60 fps, in that case the framerate is too low. Just to say that the raw FPS is not meaningful in itself._

[singleNeuron]

Could it be easier by showing it on window's title bar, it seems to be like a good idea.

[AndroidDeveloperLB]

Can you please allow to show it in either the title bar or the screen?