scmutil: improve documentation of writereporequirements()
This makes it easier to understand the difference between `writerequires()`
and `writereporequirements()`.
Differential Revision: https://phab.mercurial-scm.org/D9568
#include <Python.h>
#if PY_MAJOR_VERSION >= 3
#define PYCODETYPE PyObject
#else
#define PYCODETYPE PyCodeObject
#endif
namespace contrib
{
void initpy(const char *cselfpath);
PyObject *pyglobals();
} /* namespace contrib */