pw_containers: Add missing dependency

pw_polyfill was missing from the GN build.

Change-Id: Id89a5124b2da8e616664a8f288a22587401e76ec
Reviewed-on: https://pigweed-review.googlesource.com/c/pigweed/pigweed/+/108674
Pigweed-Auto-Submit: Wyatt Hepler <hepler@google.com>
Reviewed-by: Alexei Frolov <frolv@google.com>
Commit-Queue: Auto-Submit <auto-submit@pigweed.google.com.iam.gserviceaccount.com>
diff --git a/pw_containers/BUILD.gn b/pw_containers/BUILD.gn
index 3c8852e..8ad4956 100644
--- a/pw_containers/BUILD.gn
+++ b/pw_containers/BUILD.gn
@@ -63,7 +63,10 @@
 
 pw_source_set("vector") {
   public_configs = [ ":public_include_path" ]
-  public_deps = [ dir_pw_assert ]
+  public_deps = [
+    dir_pw_assert,
+    dir_pw_polyfill,
+  ]
   public = [ "public/pw_containers/vector.h" ]
 }