[msl-writer] Add missing include.

Need the algorithm include to build on Windows.

Bug: tint:7
Change-Id: I5691c9e30c762271c767934921fe925120a67e01
Reviewed-on: https://dawn-review.googlesource.com/c/tint/+/24522
Reviewed-by: Ryan Harrison <rharrison@chromium.org>

src/writer/msl/namer.cc

@@ -14,6 +14,8 @@
 
 #include "src/writer/msl/namer.h"
 
+#include <algorithm>
+
 namespace tint {
 namespace writer {
 namespace msl {