pw_minimal_cpp_stdlib: initializer_list

Change-Id: I9123859000705469ae5cb1f9b20c83b90bfeeedb
diff --git a/pw_minimal_cpp_stdlib/BUILD.gn b/pw_minimal_cpp_stdlib/BUILD.gn
index d9ac40f..533dbbd 100644
--- a/pw_minimal_cpp_stdlib/BUILD.gn
+++ b/pw_minimal_cpp_stdlib/BUILD.gn
@@ -36,6 +36,7 @@
     "public/cstdint",
     "public/cstdio",
     "public/cstring",
+    "public/initializer_list",
     "public/iterator",
     "public/limits",
     "public/new",
@@ -53,6 +54,7 @@
     "public/internal/cstdint.h",
     "public/internal/cstdio.h",
     "public/internal/cstring.h",
+    "public/internal/initializer_list.h",
     "public/internal/iterator.h",
     "public/internal/limits.h",
     "public/internal/new.h",