NB getError returns const char

We fixed the NB interface to have the callback return const char*
instead of char*, this commit fixes the test.

Bug: 32542970
Test: make test-art-host -j48
Change-Id: Iebab91c94dcc5699623226f220d6ef474b1a5f1f
diff --git a/test/115-native-bridge/nativebridge.cc b/test/115-native-bridge/nativebridge.cc
index 56d737f..41329af 100644
--- a/test/115-native-bridge/nativebridge.cc
+++ b/test/115-native-bridge/nativebridge.cc
@@ -466,7 +466,7 @@
   return 0;
 }
 
-extern "C" char* native_bridge_getError() {
+extern "C" const char* native_bridge_getError() {
   printf("dlerror() in native bridge.\n");
   return nullptr;
 }