* sigproc.h (no_thread_exit_protect): New class.
* sigproc.cc (thread_exit): Use no_thread_exit_protect to determine if we need
to coordinate ThreadExit/ExitProcess.
* fhandler_dsp.cc (fhandler_dev_dsp::Audio_out::stop): Use
no_thread_exit_protect to kludge around waiting for waveOutClose as it waits
for a thread that never exits.
(fhandler_dev_dsp::Audio_in::stop): Ditto for waveInClose.
* fhandler.h (fhandler_dev_dsp::base): New method.
(fhandler_dev_dsp::_read): Ditto.
(fhandler_dev_dsp::_write): Ditto.
(fhandler_dev_dsp::_ioctl): Ditto.
(fhandler_dev_dsp::_fixup_after_fork): Ditto.
(fhandler_dev_dsp::_fixup_after_exec): Ditto.
* fhandler_dsp.cc (fhandler_dev_dsp::read): Call real function via base()
pointer.
(fhandler_dev_dsp::write): Ditto.
(fhandler_dev_dsp::ioctl): Ditto.
(fhandler_dev_dsp::fixup_after_fork): Ditto.
(fhandler_dev_dsp::fixup_after_exec): Ditto.
(fhandler_dev_dsp::_read): Rename by adding an leading underscore.
(fhandler_dev_dsp::_write): Ditto.
(fhandler_dev_dsp::_ioctl): Ditto.
(fhandler_dev_dsp::_fixup_after_fork): Ditto.
(fhandler_dev_dsp::_fixup_after_exec): Ditto.
	Partially revert patch from 2014-03-04.
	* exception.h (exception::handler_installed): Declare.
	(exception::exception): Install vectored exception handler on x86_64.
	(exception::~exception): Remove for x86_64.
	* exceptions.cc (exception::handler_installed): Define.
* fhandler_dsp.cc (fhandler_dev_dsp::fixup_after_fork): Actually call
_fixup_after_fork rather than looping forever.
(fhandler_dev_dsp::fixup_after_exec): Ditto.