Fix C:\ case on windows

src/common/utils.c

@@ -35,7 +35,8 @@ int _starpu_mkpath(const char *s, mode_t mode)
 	rv = -1;
 	if (strcmp(s, ".") == 0 || strcmp(s, "/") == 0
 #ifdef __MINGW32__
-		|| (s[0] && s[1] == ':' && s[2] == '/' && !s[3])
+		/* C:/ or C:\ */
+		|| (s[0] && s[1] == ':' && (s[2] == '/' || s[2] == '\\') && !s[3])
 #endif
 		)
 		return 0;