Cygwin: fhandler_pipe::get_query_hdl_per_process: avoid a crash
NtQueryInformationProcess(ProcessHandleInformation) can return
STATUS_SUCCESS with invalid handle data for certain processes
("minimal" processes on Windows 10). This can cause a crash when
there's an attempt to access that data. Fix that by setting
NumberOfHandles to zero before calling NtQueryInformationProcess.