Merge branch 'dp/cywginstat'

* dp/cywginstat:
  cygwin: Use native Win32 API for stat
  mingw: move common functionality to win32.h
  add have_git_dir() function

cache.h

@@ -319,6 +319,7 @@ extern int is_bare_repository(void);
 extern int is_inside_git_dir(void);
 extern char *git_work_tree_cfg;
 extern int is_inside_work_tree(void);
+extern int have_git_dir(void);
 extern const char *get_git_dir(void);
 extern char *get_object_directory(void);
 extern char *get_index_file(void);