[Bug c/102989] Add Clang's _ExtInt(N)

[colomar.6.4.3 at gmail dot com via Gcc-bugs]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=102989

--- Comment #2 from Alejandro Colomar <colomar.6.4.3 at gmail dot com> ---
There was a missing comma.  Fix:

#define __STYPE_MAX(t) (((((t) 1 << (widthof(t) - 2)) - 1) << 1) + 1)