`binop_common` emits a `SKIP` that is intended to apply only to
`copysign`, but is instead applying to all binary operators. Correct the
general case but leave the currently-failing `maximum_num` tests as a
FIXME, to be resolved separately in [1].
Also simplify skip logic and NaN checking, and add a few more `copysign`
checks.
[1]: https://github.com/rust-lang/compiler-builtins/pull/939
Currently we run logspace tests for extensive tests, but there isn't any
reason we couldn't also run more kinds of tests more extensively (e.g.
more edge cases, combine edge cases with logspace for multi-input
functions, etc). As a first step toward making this possible, make
`extensive` a new field in `CheckCtx`, and rename `QuickSpaced` to
`Spaced`.
It would be nice to reuse some of the macro structure for internal
functions, like `rem_pio2`. To facilitate this, add a `public` field and
make it available in the macro's API.
Distribute everything from `libm/` to better locations in the repo.
`libm/libm/*` has not moved yet to avoid Git seeing the move as an edit
to `Cargo.toml`.
Files that remain to be merged somehow are in `etc/libm`.
