libnativeloader: remove stubs for now.

Seems to break VMDebug test.

Also add missed strdup in returned error message.

bug: 122957265
Test: VMDebug
Change-Id: I64727d707f20c0e6afcb5455edf20c99011a81dc
diff --git a/libnativeloader/native_loader.cpp b/libnativeloader/native_loader.cpp
index f231afa..af7df72 100644
--- a/libnativeloader/native_loader.cpp
+++ b/libnativeloader/native_loader.cpp
@@ -632,7 +632,7 @@
     *needs_native_bridge = false;
     void* handle = dlopen(path, RTLD_NOW);
     if (handle == nullptr) {
-      *error_msg = dlerror();
+      *error_msg = strdup(dlerror());
     }
     return handle;
   }