[PATCH 1/2] Y2038: add type __time64_t

[Joseph Myers]

There is a key definition you are missing in this patch: one that says 
whether the particular glibc configuration supports 32-bit time_t at all.

This new macro could go in bits/wordsize.h, or in its own installed 
header.  The value is normally the same as (__WORDSIZE == 32), *except* on 
x32, which already has 64-bit time_t despite 32-bit wordsize.

The new macro would be used, in the installed headers, to control whether 
an explicit _TIME_BITS=32 is valid or not.  It would also be used, in 
glibc internals, to control whether there are separate 32-bit interfaces 
that wrap 64-bit ones, or whether the 64-bit names are just #defined to 
the generic ones (#define __clock_gettime64 __clock_gettime, in some 
internal header, for example) to avoid creating any new interfaces in the 
case where time_t is already 64-bit, while avoiding the need for lots of 
conditionals where glibc-internal code written for 64-bit time_t wishes to 
call such interfaces.

-- 
Joseph S. Myers
joseph@codesourcery.com