Killing adb on close by default would be incorrect, since it would break any other usage of adb in parallel. It could be easily done manually by calling "adb kill-server" once scrcpy terminates, but add an option --kill-adb-on-close for convenience. Fixes #205 <https://github.com/Genymobile/scrcpy/issues/205> Fixes #2580 <https://github.com/Genymobile/scrcpy/issues/2580> Fixes #4049 <https://github.com/Genymobile/scrcpy/issues/4049>