Windows: always chmod(, 0666) before unlink().

On Windows, read-only files cannot be deleted. To make sure that
deletion does not fail because of this, always call chmod() before
unlink().

Signed-off-by: Johannes Schindelin <Johannes.Schindelin@gmx.de>
Signed-off-by: Johannes Sixt <johannes.sixt@telecom.at>

compat/mingw.h

@@ -106,6 +106,14 @@ static inline int mingw_mkdir(const char *path, int mode)
 }
 #define mkdir mingw_mkdir
 
+static inline int mingw_unlink(const char *pathname)
+{
+	/* read-only files cannot be removed */
+	chmod(pathname, 0666);
+	return unlink(pathname);
+}
+#define unlink mingw_unlink
+
 static inline int waitpid(pid_t pid, unsigned *status, unsigned options)
 {
 	if (options == 0)