(RHEL-6090) Add new Type=notify-reload service type for a service reload protocol based on SIGHUP #257

Advanced Commit Linter

commit	upstream
`5523df4` - sd-event: don't mistake USEC_INFINITY passed in for overflow	systemd/systemd@`ef85919`
`f7b9643` - pid1: rework service_arm_timer() to optionally take a relative time va…	systemd/systemd@`e5d6dcc`
`bb50094` - manager: add one more assert()	systemd/systemd@`7fa4928`
`d3027f5` - pid1: add new Type=notify-reload service type	systemd/systemd@`3bd28bf`
`7d246cf` - man: document Type=notify-reload	systemd/systemd@`81e19b6`
`902a48a` - pid1: make sure we send our calling service manager RELOADING=1 when r…	systemd/systemd@`dd0ab17`
`22bfa2a` - networkd: implement Type=notify-reload protocol	systemd/systemd@`0e07cdb`
`a691761` - udevd: implement the full Type=notify-reload protocol	systemd/systemd@`f843315`
`c175049` - logind: implement Type=notify-reload protocol properly	systemd/systemd@`5d71e46`
`5b017d6` - notify: add --stopping + --reloading switches	systemd/systemd@`fd0f4da`
`1bea828` - test: add Type=notify-reload testcase	systemd/systemd@`ee52bbc`
`f211957` - update TODO	systemd/systemd@`6fee784`
`d879fea` - core: check for SERVICE_RELOAD_NOTIFY in manager_dbus_is_running	systemd/systemd@`845824a`