Allow different namespace types for different classloaders

An app should be able to make cross-arch calls to different apps
via other app's Context.getClassLoader()

Bug: 32542970
Test: Boot fugu. Check that there are no linker-namespace
      related errors in the log.

Change-Id: I1593f4688bcde0121a5e24a707441a4935fa7dc4
diff --git a/libnativebridge/tests/DummyNativeBridge3.cpp b/libnativebridge/tests/DummyNativeBridge3.cpp
index c538fa0..13fce85 100644
--- a/libnativebridge/tests/DummyNativeBridge3.cpp
+++ b/libnativebridge/tests/DummyNativeBridge3.cpp
@@ -68,7 +68,7 @@
   return 0;
 }
 
-extern "C" char* native_bridge3_getError() {
+extern "C" const char* native_bridge3_getError() {
   return nullptr;
 }