Don't use native bridge for non zygote-spawn processes

... unless we force it for testing purposes.

Bug: 26954924
Change-Id: Ib4660a35175abb479d0399e18b6194eb04dbc248
diff --git a/runtime/runtime.h b/runtime/runtime.h
index c8c2ee5..bec26f8 100644
--- a/runtime/runtime.h
+++ b/runtime/runtime.h
@@ -774,6 +774,9 @@
   // building a statically link version of dex2oat.
   bool no_sig_chain_;
 
+  // Force the use of native bridge even if the app ISA matches the runtime ISA.
+  bool force_native_bridge_;
+
   // Whether or not a native bridge has been loaded.
   //
   // The native bridge allows running native code compiled for a foreign ISA. The way it works is,