Fix macOS build due to SOCK_CLOEXEC
Fixes
src/lib/util/ksignalhandler.cpp:37:45: error: use of undeclared identifier 'SOCK_CLOEXEC' if (::socketpair(AF_UNIX, SOCK_STREAM | SOCK_CLOEXEC, 0, KSignalHandlerPrivate::signalFd)) {
I'm not sure about the 2 windows build errors