std.fs: delete unused label

stage2 starting to catch problems with the standard library :)

lib/std/fs.zig

@@ -570,7 +570,7 @@ pub const Dir = struct {
             /// Memory such as file names referenced in this returned entry becomes invalid
             /// with subsequent calls to `next`, as well as when this `Dir` is deinitialized.
             pub fn next(self: *Self) Error!?Entry {
-                start_over: while (true) {
+                while (true) {
                     const w = os.windows;
                     if (self.index >= self.end_index) {
                         var io: w.IO_STATUS_BLOCK = undefined;