Fixed shutdown of context switch tracer

[akaStiX]

This change fixes issue when your profiling process is run under the debugger and you try to start context switch tracing - the first time you do it, context switch tracing will terminate itself immediately due to timeout. Visual studio will start loading debug symbols for a bunch of libs when calling ShellExecuteA and this will result into time out for cswitch trace tool on a first run. You'll have to disable and then re enable switch tracing from live view to get it running properly. That is very annoying