* dcrt0.cc (do_exit): Only call sigproc_terminate from one location --

* dcrt0.cc (do_exit): Only call sigproc_terminate from one location --
pinfo::exit.
* pinfo.cc (pinfo::exit): Move sigproc_terminate later so that signals can be
processed while waiting for hExeced child.
(pinfo::maybe_set_exit_code_from_windows): Set exit code from sigExeced if it
is non-zero.  Set exit_state to ES_EXEC_EXIT prior to waiting for captive
process exit code.
* exceptions.cc (sigExeced): New global variable.
(signal_exit): Remove noreturn attribute from declaration.
(signal_exit): Just terminate captive process and return if hExeced on the
theory that the exit will be subsequently handled in the main thread.
* sigproc.cc (sigproc_terminate): Eliminate test for ES_SIGPROCTERMINATE and
use ES_FINAL instead.
(sig_send): Use no_signals_available instead of duplicate test.
* winsup.h (ES_EXEC_EXIT): New enum.
(ES_SIGPROCTERMINATE): Delete.