Display human-readable descriptions for signal types in crash handlers

[Calinou]

• Follow-up to Color stacktraces printed by the crash handler when in a TTY #33505 and Show a GUI alert when crashing on desktop platforms #61906.

Previously, only the signal number was displayed:

handle_crash: Program crashed with signal 4

Now, the signal code and description are shown:

handle_crash: Program crashed with signal 4 (SIGILL) - Illegal instruction

This only affects Linux and macOS, not Windows.

[Riteo]

Nice! My bit/signal.h header has more signals. Should we add a description for them all? I guess we could use #ifdefs or perhaps follow a standard if there's any.

Excerpt from my bit/signal.h:

#define SIGHUP    1
#define SIGINT    2
#define SIGQUIT   3
#define SIGILL    4
#define SIGTRAP   5
#define SIGABRT   6
#define SIGIOT    SIGABRT
#define SIGBUS    7
#define SIGFPE    8
#define SIGKILL   9
#define SIGUSR1   10
#define SIGSEGV   11
#define SIGUSR2   12
#define SIGPIPE   13
#define SIGALRM   14
#define SIGTERM   15
#define SIGSTKFLT 16
#define SIGCHLD   17
#define SIGCONT   18
#define SIGSTOP   19
#define SIGTSTP   20
#define SIGTTIN   21
#define SIGTTOU   22
#define SIGURG    23
#define SIGXCPU   24
#define SIGXFSZ   25
#define SIGVTALRM 26
#define SIGPROF   27
#define SIGWINCH  28
#define SIGIO     29
#define SIGPOLL   29
#define SIGPWR    30
#define SIGSYS    31
#define SIGUNUSED SIGSYS

[RedworkDE]

Should we add a description for them all?

The signal handler is only registered for SIGSEGV, SIGFPE, and SIGILL, so the other cases are dead anyways.

godot/platform/linuxbsd/crash_handler_linuxbsd.cpp

Lines 189 to 193 in 9b3f13d

	#ifdef CRASH_HANDLER_ENABLED
	signal(SIGSEGV, handle_crash);
	signal(SIGFPE, handle_crash);
	signal(SIGILL, handle_crash);
	#endif

(same for macos)

[Riteo]

@RedworkDE

The signal handler is only registered for SIGSEGV, SIGFPE, and SIGILL, so the other cases are dead anyways.

Mh, this PR humanizes a few (arguably useful) extra signals though, so we either remove them from this PR or register them.

[Calinou]

I don't think we should add more signals to the crash handler, so I think it's best to remove the extra cases I added.