At least, when there's not a ZigObject. The old behavior was incorrect
in the presence of a ZigObject, and this doesn't really mix nicely with
incremental compilation anyway; but when the objects are all external,
we may as well build the search table.
Far simpler, because everything which `crash_report.zig` did is now
handled pretty well by `std.debug` anyway. All we want is to print some
context around panics and segfaults. Using the new ability to override
the default segfault handler while still having std handle the
target-specific bits for us, that's really simple.
The downside of this commit is that more precise errors are no longer
propagated up. However, these errors were pretty useless in isolation
due to them having no context; and regardless, we intentionally swallow
most of them in `std.debug` anyway. Therefore, this is better in
practice, because it allows `std.debug` to give slightly more useful
warnings when handling errors. This commit does that for unwind errors,
for instance, which differentiate between the unwind info being corrupt
vs missing vs inaccessible vs unsupported.
A better solution would be to also include more detailed information via
the diagnostics pattern, but this commit is an incremental improvement.
turns out this isn't technically specific to that target at all; other
targets just don't emit mid-function 'ret' instructions as much so
certain CFI instruction patterns were only seen on aarch64.
thanks to jacob for finding the bug <3
Because -fno-llvm is now the default on x86_64-linux, this target was
exactly equivalent to one specified earlier in the matrix. This was
probably just missed when doing the work to enable the self-hosted
backend by default for x86_64.
