Most coredumps contain large amounts of consecutive null bytes and as
such are a prime candidate for compression.
This commit makes CrashDaemon compress files once the kernel finishes
emitting them, as well as adds the functionality needed in LibCoreDump
to then parse them.
This was needlessly expecting the first backtrace entry function name to
start with '__assertion_failed', which is no longer the case - it's now
something from libsystem.so. Let's just check whether we have an
'assertion' key in the coredump's metadata, just like we do for pledge
violations.
Now that WindowServer broadcasts the system theme using an anonymous
file, we need clients to pledge "recvfd" so they can receive it.
Some programs keep the "shared_buffer" pledge since it's still used for
a handful of things.
This is in preparation of adding (much) more process information to
coredumps. As we can only have one null-terminated char[] of arbitrary
length in each struct it's now a single JSON blob, which is a great fit:
easily extensible in the future and allows for key/value pairs and even
nested objects, which will be used e.g. for the process environment, for
example.
