[Toybox] ftpget - Fixes and minor new features.

[Rob Landley]

On 11/2/21 2:00 PM, Eric Molitor wrote:
> Attention should be paid to the change to portability.h. I believe this is the
> correct way to expose memrchr for glibc. I've tested it and it works with glibc
> but I primarily use MUSL.

I'm uncomfortable trying to guess which combinations of const and restrict a
nonstandard header prototype is going to have from version to version and
library to library.

That's why I did timer_create_wrap() with a #define from the old name instead of
just implementing something to match the header that would bind first before
going out to libraries: I don't trust any header with "const" or "restrict" in
it... and the #define from the old name is breaking android NDK because when
they DO get around to #including the header it renames the prototype to the new
function.

And the stanza is triggering on the NDK because they don't have -lrt. So if we
don't -lrt on the probe gcc fails, and if we DO clang fails. Bravo. Eh, probe
without -lrt because it's really a gcc bug: libgcc_eh.a should not be making
thread calls in non-threaded programs. This means we always wrap on glibc, and
I'm ok with that.

Rob