This is the second part of the P3370R1 proposal just approved by the
committee in Wrocław. This adds C++ equivalents of the functions added
to C23 by WG14 N2683.
These functions are in the global namespace, but to avoid collisions
with the same functions defined by other standard library
implementations, this change defines them in namespace __gnu_cxx and
then adds them to the global namespace.
libstdc++-v3/ChangeLog:
* include/Makefile.am: Add stdckdint.h.
* include/Makefile.in: Regenerate.
* src/c++23/std.compat.cc.in: Export <stdckdint.h> functions.
* include/c_compatibility/stdckdint.h: New file.
* testsuite/26_numerics/stdckdint/1.cc: New test.
* testsuite/26_numerics/stdckdint/2_neg.cc: New test.
Reviewed-by: Patrick Palka <ppalka@redhat.com>