cext: fix for PyLong refactoring in CPython 3.12
Compiling Mercurial with Python 3.12 a5 would fail with:
mercurial/cext/dirs.c: In function '_addpath':
mercurial/cext/dirs.c:19:44: error: 'PyLongObject' {aka 'struct _longobject'} has no member named 'ob_digit'
19 | #define PYLONG_VALUE(o) ((PyLongObject *)o)->ob_digit[0]
| ^~
mercurial/cext/dirs.c:97:25: note: in expansion of macro 'PYLONG_VALUE'
97 | PYLONG_VALUE(val) += 1;
| ^~~~~~~~~~~~
mercurial/cext/dirs.c:19:44: error: 'PyLongObject' {aka 'struct _longobject'} has no member named 'ob_digit'
19 | #define PYLONG_VALUE(o) ((PyLongObject *)o)->ob_digit[0]
| ^~
mercurial/cext/dirs.c:108:17: note: in expansion of macro 'PYLONG_VALUE'
108 | PYLONG_VALUE(val) = 1;
| ^~~~~~~~~~~~
mercurial/cext/dirs.c: In function '_delpath':
mercurial/cext/dirs.c:19:44: error: 'PyLongObject' {aka 'struct _longobject'} has no member named 'ob_digit'
19 | #define PYLONG_VALUE(o) ((PyLongObject *)o)->ob_digit[0]
| ^~
mercurial/cext/dirs.c:145:23: note: in expansion of macro 'PYLONG_VALUE'
145 | if (--PYLONG_VALUE(val) <= 0) {
| ^~~~~~~~~~~~
This was caused by
https://github.com/python/cpython/commit/c1b1f51cd1632f0b77dacd43092fb44ed5e053a9 .