[Merge] lp:~stgraber/upstart/upstart-prctl into lp:upstart

[Stéphane Graber]

So I ended up doing it in a slightly different way, based on what systemd and gnome are doing.

Basically, moving all the prctl stuff under an ifdef and having the subreaper value hardcoded in cases where it's not defined in prctl.h.

This should cover systems that for some reason lack prctl.h, systems that have prctl.h but miss the subreaper definition and systems that have older kernels where the subreaper option doesn't exist.

On systems that don't have prctl.h, the code will be entirely skipped and no event will be emitted.
On systems that have prctl.h but where the subreaper isn't defined or isn't supported by the kernel, the event will be emitted. 
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https://code.launchpad.net/~stgraber/upstart/upstart-prctl/+merge/136759
Your team Upstart Reviewers is requested to review the proposed merge of lp:~stgraber/upstart/upstart-prctl into lp:upstart.