The libc++ upgrade means we can use contains() in the linker now.

Change-Id: I30f764ddfd101dde1b7bbcefbf78182a19b3db7c
diff --git a/linker/linker_namespaces.cpp b/linker/linker_namespaces.cpp
index 5182129..eb9dae9 100644
--- a/linker/linker_namespaces.cpp
+++ b/linker/linker_namespaces.cpp
@@ -100,7 +100,7 @@
     // be searched.
     if (allow_secondary) {
       const android_namespace_list_t& secondary_namespaces = si->get_secondary_namespaces();
-      if (secondary_namespaces.find(this) != secondary_namespaces.end()) {
+      if (secondary_namespaces.contains(this)) {
         return true;
       }
     }