features-time64.h on non-linux 32b platforms

Hello,

We got a report that when defining _TIME_BITS to 64 on a non-linux 32bit
platform, one does not get time64 variants, and not even a warning about
that. I'm thinking that most of
./sysdeps/unix/sysv/linux/features-time64.h could be moved to
sysdeps/generic, and keep this linux-only:

#if defined __USE_TIME_BITS64 && __TIMESIZE == 32
# define __USE_TIME64_REDIRECTS 1
#endif

and turn it into this in sysdeps/generic:

#if defined __USE_TIME_BITS64 && __TIMESIZE == 32
# error "_TIME_BITS=64 is not supported on this 32-bit platform"
#endif

?

With regards,
Samuel