Remove several race conditions with signal handler (bug #61370). This patch removes several race conditions between the interpreter and the Ctrl-C signal handler, as described in more detail in bug #61370. * libinterp/corefcn/sighandlers.h: Make can_interrupt atomic. * libinterp/corefcn/sighandlers.cc: Make can_interrupt, signals_caught atomic, use atomic value read for signals_caught, octave_interrupt_state, change 1 to true. * liboctave/util/quit.h: Move octave_interrupt_state and octave_signal_caught to C++ only code, rewrite octave_quit() function, rewrite OCTAVE_QUIT macro to use octave_quit_c() function. * liboctave/util/quit.cc: Make octave_interrupt_state and octave_signal_caught atomic, add new wrapper function octave_quit_c(). * libinterp/corefcn/interpreter.h: Make octave_initialized atomic. * libinterp/corefcn/interpreter.cc: Make octave_initialized atomic, change 0 to false. * liboctave/util/action-container.h: New namespace "util", make m_val atomic. * liboctave/util/oct-atomic.c: Reorder preprocessor if-elif-else ladder. * liboctave/util/cmd-edit.cc: Change 0 to false.

--- a/liboctave/util/cmd-edit.cc	Mon Feb 20 18:06:54 2023 -0800
+++ b/liboctave/util/cmd-edit.cc	Tue Feb 21 17:45:34 2023 -0500
@@ -785,7 +785,7 @@
 void
 gnu_readline::do_handle_interrupt_signal ()
 {
-  octave_signal_caught = 0;
+  octave_signal_caught = false;
   octave_interrupt_state = 0;
 
   ::octave_rl_recover_from_interrupt ();