Fix longlong.h for use outside GCC

[Roland McGrath]

> I'll let you and Roland sort this out then... he asked me to resync
> with GCC in preference to merging bits.  I'm completely indifferent as
> long as I get to fix ARM's broken printf.

I just don't want to try to review changes to the bits myself or worry
about whose review to rely on, and "got committed to GCC" is a handily
comfortable standard for glibc.  Also, in the long run I really don't want
to have divergence between gcc and glibc files that could be in unison.
So, whatever works for the short run, as long as they are unified before
there are many more individual changes to consider.


Thanks,
Roland