merge(third_party/git): Merge squashed git subtree at v2.23.0

Merge commit '1b593e1ea4' as 'third_party/git'

third_party/git/compat/msvc.h

@@ -0,0 +1,33 @@
+#ifndef __MSVC__HEAD
+#define __MSVC__HEAD
+
+#include <direct.h>
+#include <process.h>
+#include <malloc.h>
+#include <io.h>
+
+#pragma warning(disable: 4018) /* signed/unsigned comparison */
+#pragma warning(disable: 4244) /* type conversion, possible loss of data */
+#pragma warning(disable: 4090) /* 'function' : different 'const' qualifiers (ALLOC_GROW etc.)*/
+
+/* porting function */
+#define inline __inline
+#define __inline__ __inline
+#define __attribute__(x)
+#define strcasecmp   _stricmp
+#define strncasecmp  _strnicmp
+#define ftruncate    _chsize
+#define strtoull     _strtoui64
+#define strtoll      _strtoi64
+
+#undef ERROR
+
+#define ftello _ftelli64
+
+typedef int sigset_t;
+/* open for reading, writing, or both (not in fcntl.h) */
+#define O_ACCMODE     (_O_RDONLY | _O_WRONLY | _O_RDWR)
+
+#include "compat/mingw.h"
+
+#endif