Refactor the signal handler

[Buristan]

For now signal hanlder use exit() which is not async-signal-safe, see man 7 signal-safety. It is better to use _exit() instead.

luzer/luzer/luzer.c

Lines 147 to 157 in d2cb24d

	NO_SANITIZE static void
	sig_handler(int sig)
	{
	switch (sig) {
	case SIGINT:
	exit(0);
	case SIGSEGV:
	__sanitizer_print_stack_trace();
	break;
	}
	}

Also, sometimes the crash- file is dumped if the user tries just to stop execution by SIGINT, so this file is not needed and is confusing.

[ligurio]

The problem can be reproduced by the following command line (note a value in -jobs option):

luajit luzer/tests/test_e2e.lua -jobs=-1 -runs=2

Core was generated by `/home/burii/builds_workspace/luajit/fuzzing/src/luajit /home/burii/reviews/ligurio-luzer/ligurio-luzer/luzer/tests/test_e2e.lua -jobs=-1
 -runs=2'.
Program terminated with signal SIGSEGV, Segmentation fault.
#0  0x00007fc3c627331f in fuzzer::Fuzzer::InterruptExitCode() ()
    at /var/tmp/portage/llvm-runtimes/compiler-rt-sanitizers-19.1.7/work/compiler-rt/lib/fuzzer/FuzzerLoop.cpp:265

warning: 265    /var/tmp/portage/llvm-runtimes/compiler-rt-sanitizers-19.1.7/work/compiler-rt/lib/fuzzer/FuzzerLoop.cpp: No such file or directory
[Current thread is 1 (Thread 0x7fc3bffff6c0 (LWP 964))]
warning: File "/home/burii/builds_workspace/luajit/fuzzing/src/luajit-gdb.py" auto-loading has been declined by your `auto-load safe-path' set to "$debugdir:$d
atadir/auto-load".
To enable execution of this file add
        add-auto-load-safe-path /home/burii/builds_workspace/luajit/fuzzing/src/luajit-gdb.py
line to your configuration file "/home/burii/.gdbinit".
To completely disable this security protection add
        set auto-load safe-path /
line to your configuration file "/home/burii/.gdbinit".
For more information about this security protection see the
"Auto-loading safe path" section in the GDB manual.  E.g., run from the shell:
        info "(gdb)Auto-loading safe path"
(gdb) bt
#0  0x00007fc3c627331f in fuzzer::Fuzzer::InterruptExitCode() ()
    at /var/tmp/portage/llvm-runtimes/compiler-rt-sanitizers-19.1.7/work/compiler-rt/lib/fuzzer/FuzzerLoop.cpp:265
#1  0x00007fc3c629114d in ExecuteCommand () at /var/tmp/portage/llvm-runtimes/compiler-rt-sanitizers-19.1.7/work/compiler-rt/lib/fuzzer/FuzzerUtilLinux.cpp:31
#2  0x00007fc3c62620c9 in WorkerThread () at /var/tmp/portage/llvm-runtimes/compiler-rt-sanitizers-19.1.7/work/compiler-rt/lib/fuzzer/FuzzerDriver.cpp:244
#3  0x00007fc3c5ce6144 in std::execute_native_thread_routine (__p=0x56339c4fdff0)
    at /var/tmp/portage/sys-devel/gcc-14.2.1_p20241221/work/gcc-14-20241221/libstdc++-v3/src/c++11/thread.cc:104
#4  0x00007fc3c6383efa in start_thread () from /lib64/libc.so.6
#5  0x00007fc3c64053ac in __clone3 () from /lib64/libc.so.6