fixup??? mingw: make the dirent implementation pluggable

This is necessary because the win+Meson build now uses a GCC that seems
to link to `libmingwex.a` under certain circumstances (a static libcurl
build seemingly falling into that category) where `opendir` is already
defined as a variable. _sigh_

Signed-off-by: Johannes Schindelin <[email protected]>

Author: dscho

compat/win32/dirent.h

@@ -23,6 +23,8 @@ typedef struct DIR {
 /* default dirent implementation */
 extern DIR *dirent_opendir(const char *dirname);
 
+#define opendir git_opendir
+
 /* current dirent implementation */
 extern DIR *(*opendir)(const char *dirname);