Add more info to class initialization check

A check in class_linker.cc is occasionally failing on buildbots. Add
more information to it to assist in figuring out the issue.

Test: Build
Change-Id: I70d8b8ebefa7f53fc136fabb89482c0132e39b8c
diff --git a/runtime/class_linker.cc b/runtime/class_linker.cc
index 9c0ccee..1f4489a 100644
--- a/runtime/class_linker.cc
+++ b/runtime/class_linker.cc
@@ -267,7 +267,9 @@
   // cannot in general be guaranteed, but in all likelihood leads to breakage down the line.
   if (klass->GetClassLoader() == nullptr && !Runtime::Current()->IsAotCompiler()) {
     std::string tmp;
-    LOG(kIsDebugBuild ? FATAL : WARNING) << klass->GetDescriptor(&tmp) << " failed initialization";
+    LOG(kIsDebugBuild ? FATAL : WARNING) << klass->GetDescriptor(&tmp)
+                                         << " failed initialization: "
+                                         << self->GetException()->Dump();
   }
 
   env->ExceptionClear();