rust-index: using the `hg::index::Index` in ancestors iterator and lazy set Since there is no Rust implementation for REVLOGV2/CHANGELOGv2, we declare them to be incompatible with Rust, hence indexes in these formats will use the implementations from Python `mercurial.ancestor`. If this is an unacceptable performance hit for current users of these formats, we can later on add Rust implementations based on the C index for them or implement these formats for the Rust indexes. Among the challenges that we had to meet, we wanted to avoid taking the GIL each time the inner (vcsgraph) iterator has to call the parents function. This would probably still be acceptable in terms of performance with `AncestorsIterator`, but not with `LazyAncestors` nor for the upcoming change in `MissingAncestors`. Hence we enclose the reference to the index in a `PySharedRef`, leading to more rigourous checking of mutations, which does pass now that there no logically immutable methods of `hg::index::Index` that take a mutable reference as input.

#ifndef HG_COMPAT_H
#define HG_COMPAT_H

#ifdef _WIN32
#ifdef _MSC_VER
#if _MSC_VER < 1900
/* msvc 6.0 has problems */
#define inline __inline
#if defined(_WIN64)
typedef __int64 ssize_t;
typedef unsigned __int64 uintptr_t;
#else
typedef int ssize_t;
typedef unsigned int uintptr_t;
#endif
typedef signed char int8_t;
typedef short int16_t;
typedef long int32_t;
typedef __int64 int64_t;
typedef unsigned char uint8_t;
typedef unsigned short uint16_t;
typedef unsigned long uint32_t;
typedef unsigned __int64 uint64_t;
#else
/* VC++ 14 */
#include <stdint.h>

#if defined(_WIN64)
typedef __int64 ssize_t;
#else
typedef int ssize_t;
#endif
#endif /* _MSC_VER < 1900 */

#else
/* not msvc */
#include <stdint.h>
#endif
#else
/* not windows */
#include <sys/types.h>
#if defined __BEOS__ && !defined __HAIKU__
#include <ByteOrder.h>
#else
#include <arpa/inet.h>
#endif
#include <inttypes.h>
#endif

#if defined __hpux || defined __SUNPRO_C || defined _AIX
#define inline
#endif

#ifdef __linux
#define inline __inline
#endif

#endif