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

Change-Id: I30f764ddfd101dde1b7bbcefbf78182a19b3db7c
diff --git a/linker/linker_soinfo.cpp b/linker/linker_soinfo.cpp
index 802c06a..d915503 100644
--- a/linker/linker_soinfo.cpp
+++ b/linker/linker_soinfo.cpp
@@ -887,7 +887,7 @@
     handle_ = handle_ | 1;
   } while (handle_ == reinterpret_cast<uintptr_t>(RTLD_DEFAULT) ||
            handle_ == reinterpret_cast<uintptr_t>(RTLD_NEXT) ||
-           g_soinfo_handles_map.find(handle_) != g_soinfo_handles_map.end());
+           g_soinfo_handles_map.contains(handle_));
 
   g_soinfo_handles_map[handle_] = this;
 }