Change foo (void) to foo () for all c++ functions throughout. Remove all

Change foo (void) to foo () for all c++ functions throughout.  Remove all
fhandler_*::dump functions throughout.
* fhandler.h (fhandler_dev_mem::close): Remove pass-through function in favor
of virtual method.
(handler_dev_raw::close): Ditto.
(fhandler_dev_clipboard::fixup_after_exec): New method.
* fhandler_dev_mem.cc (fhandler_dev_mem::close): Eliminate pass through
* fhandler_dev_raw.cc (fhandler_dev_raw::close): Ditto.
* fhandler_clipboard.cc (fhandler_dev_clipboard::close): Don't go to extra
effort when execing.
(fhandler_dev_clipboard::fixup_after_exec): New function.
* fhandler_console.cc (fhandler_console::close): Don't do "extra stuff" when we
know we're execing.
* fhandler_disk_file.cc (fhandler_disk_file::close): Ditto.
* fhandler_dsp.cc (fhandler_dev_dsp::close): Ditto.
* fhandler_fifo.cc (fhandler_fifo.cc::close): Ditto.  function in favor of base
function.
* fhandler_random.cc (fhandler_dev_random::close): Ditto.
* fhandler_registry.cc (fhandler_registry::close): Ditto.
* fhandler_tty.cc (fhandler_tty_slave::close): Ditto.
* fhandler_virtual.cc (fhandler_virtual::close): Ditto.
* pinfo.cc (proc_waiter): Remove unneeded hExeced declaration.
* sigproc.cc: Ditto.
* winsup.h (hExeced): Define here.
* fhandler_virtual.cc (fhandler_virtual::fixup_after_exec): Just call close()
to reinitialize things to known state.