Ignore -Wdeprecated on windows standalone build

Since we upgraded to clang 16 for the standalone build, the build fails
on windows with a -Wdeprecated warning.

This commit disables the warning.

Change-Id: I821b9a509de29684788d0ae7ffb623f4fe81d7c6
diff --git a/gn/standalone/BUILD.gn b/gn/standalone/BUILD.gn
index 582e9b8..8874a24 100644
--- a/gn/standalone/BUILD.gn
+++ b/gn/standalone/BUILD.gn
@@ -167,6 +167,13 @@
     ]
   }
 
+  if (is_clang && is_win) {
+    # clang-cl from version 16 does not like out-of-line definition of static
+    # constexpr, even in C++14 mode. Disable the deprecated warnings to work
+    # around the problem.
+    cflags += [ "-Wno-deprecated" ]
+  }
+
   if (is_win) {
     cflags += [
       "/bigobj",  # Some of our files are bigger than the regular limits.