Genie:  Make Process non-copyable
Genie:  Unfactor SignalReceiver into Process
Genie:  GetPendingSignals() -> signals_pending()
Genie:  GetBlockedSignals() -> signals_blocked()
Genie:  AddPendingSignal() -> set_pending_signal()
Genie:  ClearPendingSignalSet() -> clear_pending_signal()
Genie:  ClearPendingSignals() -> clear_signals_pending()
Genie:  BlockSignals() -> block_signals()
Genie:  UnblockSignals() -> unblock_signals()
Genie:  SetBlockedSignals() -> set_signals_blocked()
Merge branch 'sigmask-methods' into sigprocmask
Genie:  Move signal mask methods to relix::thread
Genie:  Unduplicate signal-packing logic
Genie -> relix:  Move sigprocmask()
Merge branch 'sigprocmask'