[Toybox] toys/android/log.c with android NDK?

[Rob Landley]

I grabbed the current ndk (-r16b), make_standalone_toolchain.py'd an --arch
x86_64 --api 26 toolchain, and then built defconfig toybox with it, and at link
time it failed to find:

 '__android_log_write'
 'facilitynames'
 'getgrgid_r'
 'iconv'
 'iconv_open'
 'prioritynames'
 'sethostname'
 'stderr'
 'stdin'
 'stdout'

I've mentioned stdin/stdout/stderr here before. sethostname() is a trivial
syscall wrapper, iconv() and iconv_open() I _know_ bionic has because I
complained about them being implemented in c++, android_log_write() is your own
function (and the double underscore is confusing)...

More to the point all of this _compiled_, meaning it's in the headers. And then
it couldn't find it in the libraries. So there's a consistency issue somewhere.

I can try to fix it up in lib/portability.c...?

Rob