[Bug c/84764] Wrong warning "so large that it is unsigned" for __int128 constant

[joseph at codesourcery dot com]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=84764

--- Comment #5 from joseph at codesourcery dot com <joseph at codesourcery dot com> ---
Also, for it to become an extended integer type, it would be necessary to 
define integer constant suffixes and implement printf / scanf support in 
the library, because <stdint.h> is now required to provide intN_t / 
uintN_t when there is a matching standard or extended integer type, so 
would be required to provide int128_t / uint128_t, which in turn would 
require the corresponding <stdint.h> and <inttypes.h> macros, so requiring 
constant suffixes and printf / scanf support.