Use kill() over raise() for raising the signal (fixes osx 10.14 with kqueue)

Use kill() over raise() for raising the signal (fixes osx 10.14 with kqueue)

On OSX 10.14+ the raise() uses pthread_kill() (verified with dtruss) and
by some reason signals that has been raised with pthread_kill() do not
received by kqueue EVFILT_SIGNAL.

While on OSX 10.11 the raise()/pthread_kill() uses plain kill() and
everything work just fine (linux also does the same, but instead of
kill() it uses tgkill())

Here is a simple reproducer that installs alarm to show that the signal
does not received by the kqueue backend:
  https://gist.github.com/azat/73638b8e3b0fa563a20dadcca9e652a1

Refs: #747
Fixes: #765