Update longlong.h.

Update longlong.h.

This patch updates longlong.h from GCC.  There were no local changes
in glibc (the previous version was identical to the r232143 GCC
version, apart from copyright dates which had been updated in both
places), so this patch makes it identical to the version in GCC again.

Tested for x86_64 and x86.  Also tested with build-many-glibcs.py for
its RISC-V configurations, as the glibc architecture with the most
substantial changes in longlong.h in this patch.

	* stdlib/longlong.h: Update from GCC.