generally be honored. However, some signals are explicitly unblocked:
the synchronous signals, SIGILL, SIGTRAP, SIGSTKFLT, SIGCHLD, SIGPROF,
and, on Linux, signals 32 (SIGCANCEL) and 33 (SIGSETXID)
(SIGCANCEL and SIGSETXID are used internally by glibc). Subprocesses
started by [os.Exec], or by [os/exec], will inherit the
modified signal mask.

# Changing the behavior of signals in Go programs

	/* 29 */ {_SigNotify, "SIGIO: i/o now possible"},
	/* 30 */ {_SigNotify, "SIGPWR: power failure restart"},
	/* 31 */ {_SigThrow, "SIGSYS: bad system call"},
	/* 32 */ {_SigSetStack + _SigUnblock, "signal 32"}, /* SIGCANCEL; see issue 6997 */
	/* 33 */ {_SigSetStack + _SigUnblock, "signal 33"}, /* SIGSETXID; see issues 3871, 9400, 12498 */
	/* 34 */ {_SigSetStack + _SigUnblock, "signal 34"}, /* musl SIGSYNCCALL; see issue 39343 */

	/*  30 */ {_SigNotify, "SIGXCPU: cpu limit exceeded"},
	/*  31 */ {_SigNotify, "SIGXFSZ: file size limit exceeded"},
	/*  32 */ {_SigSetStack + _SigUnblock, "signal 32"}, /* SIGCANCEL; see issue 6997 */
	/*  33 */ {_SigSetStack + _SigUnblock, "signal 33"}, /* SIGSETXID; see issues 3871, 9400, 12498 */
	/*  34 */ {_SigSetStack + _SigUnblock, "signal 34"}, /* musl SIGSYNCCALL; see issue 39343 */

	/* 34 */ {_SigNotify, "SIGFREEZE: special signal used by CPR"},
	/* 35 */ {_SigNotify, "SIGTHAW: special signal used by CPR"},
	/* 36 */ {_SigSetStack + _SigUnblock, "SIGCANCEL: reserved signal for thread cancellation"}, // Oracle's spelling of cancellation.
	/* 37 */ {_SigNotify, "SIGLOST: resource lost (eg, record-lock lost)"},
	/* 38 */ {_SigNotify, "SIGXRES: resource control exceeded"},

	EXFULL          = syscall.Errno(0x34)
)

// Signals
const (
	SIGABRT    = syscall.Signal(0x6)
	SIGALRM    = syscall.Signal(0xe)
	SIGBUS     = syscall.Signal(0xa)
	SIGCANCEL  = syscall.Signal(0x24)
	SIGCHLD    = syscall.Signal(0x12)
	SIGCLD     = syscall.Signal(0x12)
	SIGCONT    = syscall.Signal(0x19)
	SIGEMT     = syscall.Signal(0x7)
	SIGFPE     = syscall.Signal(0x8)

		// mstart(), the combined runtime can deadlock if
		// these signals are blocked. Thus, don't block these
		// signals when exiting threads.
		// - glibc: SIGCANCEL (32), SIGSETXID (33)
		// - musl: SIGTIMER (32), SIGCANCEL (33), SIGSYNCCALL (34)
		sigdelset(&res, 32)
		sigdelset(&res, 33)
		sigdelset(&res, 34)
	}

	return res
}()

		//
		// QEMU turns calls to the sigaction system call into
		// calls to the C library sigaction call; the C
		// library call rejects attempts to call sigaction for
		// SIGCANCEL (32) or SIGSETXID (33).
		//
		// QEMU rejects calling sigaction on SIGRTMAX (64).
		//
		// Just ignore the error in these case. There isn't
		// anything we can do about it anyhow.

	EXDEV           = Errno(0x12)
	EXFULL          = Errno(0x34)
)

// Signals
const (
	SIGABRT    = Signal(0x6)
	SIGALRM    = Signal(0xe)
	SIGBUS     = Signal(0xa)
	SIGCANCEL  = Signal(0x24)
	SIGCHLD    = Signal(0x12)
	SIGCLD     = Signal(0x12)
	SIGCONT    = Signal(0x19)
	SIGEMT     = Signal(0x7)
	SIGFPE     = Signal(0x8)
	SIGFREEZE  = Signal(0x22)
	SIGHUP     = Signal(0x1)