Security and patch rollup for FPR20 from ESR68

[classilla]

Including https://hg.mozilla.org/mozilla-central/rev/5591af7fd283

[classilla]

M1607742 https://hg.mozilla.org/releases/mozilla-esr68/rev/5da0d4b486f8c3801ecf6db42ca867d716880130
M1546191 unaffected
M1584490 (above)

[classilla]

Through a093b204c573f0df37c831aeb4ca694d05da20a5

Not relevant:
M1592078 (unaffected)
M1546191 (Fennec)
M1588197 (not required)
M1543331 (unaffected)
M1614535 (no Widevine)
M1584035 (no APZ)
M1604847 (code does not exist)
M1588248 (code does not exist)

Deferred:
M1616661 I don't think AirPods work with Power Macs.

I'd like to see if we can get something like webcompat working in TenFourFox (see M1618128).

Candidates:
M1613943 https://hg.mozilla.org/releases/mozilla-esr68/rev/07dc3b6a2642
M1608256 https://hg.mozilla.org/releases/mozilla-esr68/rev/963fcf01cc55 (We don't have everything this removes, so it should be smaller.) (JS)
M1613765 https://hg.mozilla.org/releases/mozilla-esr68/rev/49a71f8da376 https://hg.mozilla.org/releases/mozilla-esr68/rev/818216eb93bd (to sctp/src/netinet) (second patch needs some work)
M1614971 https://hg.mozilla.org/releases/mozilla-esr68/rev/5e8b71ce4e88fcdda726a0695c7b582c6a7fc481 (only audiounit_uninstall_device_changed_callback needed)