Fix C++ CameraServer request handling.
Fix C++ CameraServer request handling.

The request is not guaranteed to be in a single packet, so it may be necessary
to perform multiple reads to get the complete request.  The previous code
could unpredictably fail as it only performed a single read.

Fixes artf4817.

Change-Id: I7734a12e1a2542f5d7ca0889453c387f0bb30538

robotdotnet/allwpilib,JLLeitschuh/allwpilib,JLLeitschuh/allwpilib,PeterMitrano/allwpilib,PeterMitrano/allwpilib,robotdotnet/allwpilib,PatrickPenguinTurtle/allwpilib,PatrickPenguinTurtle/allwpilib,robotdotnet/allwpilib,JLLeitschuh/allwpilib,PatrickPenguinTurtle/allwpilib,333fred/allwpilib,robotdotnet/allwpilib,robotdotnet/allwpilib,robotdotnet/allwpilib,333fred/allwpilib,333fred/allwpilib,JLLeitschuh/allwpilib,JLLeitschuh/allwpilib,333fred/allwpilib,333fred/allwpilib,PatrickPenguinTurtle/allwpilib,JLLeitschuh/allwpilib,333fred/allwpilib,PeterMitrano/allwpilib,PeterMitrano/allwpilib,PeterMitrano/allwpilib,PatrickPenguinTurtle/allwpilib,PeterMitrano/allwpilib,PatrickPenguinTurtle/allwpilib,PeterMitrano/allwpilib,JLLeitschuh/allwpilib,PatrickPenguinTurtle/allwpilib