[native bridge] Make sure we always unload the native bridge

libnativebridge may allocate some resources during loading and
intialization and de-allocate them when unloading. This makes sure that
we don't leak anything.

Bug: 18097480
Change-Id: I901f2d3c2ab1efb2875388f99e8c5c111ce82d5a
diff --git a/runtime/native_bridge_art_interface.h b/runtime/native_bridge_art_interface.h
index 026cd82..090cddb 100644
--- a/runtime/native_bridge_art_interface.h
+++ b/runtime/native_bridge_art_interface.h
@@ -26,7 +26,7 @@
 // Mirror libnativebridge interface. Done to have the ART callbacks out of line, and not require
 // the system/core header file in other files.
 
-void LoadNativeBridge(std::string& native_bridge_library_filename);
+bool LoadNativeBridge(std::string& native_bridge_library_filename);
 
 // This is mostly for testing purposes, as in a full system this is called by Zygote code.
 void PreInitializeNativeBridge(std::string dir);