Cygwin: fhandler_pipe::get_query_hdl_per_process: avoid a crash

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.

Addresses: https://cygwin.com/pipermail/cygwin-patches/2021q4/011611.html