Bug 1091994 - Fix syscall numbers in GonkDiskSpaceWatcher. r=dhylands

Linux syscall numbers vary by architecture, so hard-coding the ARM ones
breaks non-ARM architectures.  This patch ifdefs the hard-coding, and
uses the system headers' values if/when it provides them (on Android/B2G
the headers are often significantly older than the running kernel).

Bonus fix: warning message typo, and don't assume NS_WARNING can't set errno.
Bug 1092368 - alt-svc-04. r=hurley
Bug 1078153 - capture the callback in a generated function object to prevent it becomes dead during GC. r=khuey
Bug 1083347 - Patch to remove entries in androidx86.json and annotate manifests. r=gbrown