Avoid std::string allocations for finding an array class.

Introduce ClassLinker::FindArrayClass which performs an array class lookup
given the element/component class. This has a 16 element cache of recently
looked up arrays.
Pass the current thread to ClassLinker Find .. Class routines to avoid calls
to Thread::Current().
Avoid some uses of FindClass in the debugger where WellKnownClasses is a
faster and more compacting GC friendly alternative.

Change-Id: I60e231820b349543a7edb3ceb9cf1ce92db3c843
diff --git a/runtime/mirror/class.cc b/runtime/mirror/class.cc
index 3208de9..6dbb29d 100644
--- a/runtime/mirror/class.cc
+++ b/runtime/mirror/class.cc
@@ -72,7 +72,7 @@
             << PrettyClass(this) << " " << old_status << " -> " << new_status;
     }
   }
-  if (new_status == kStatusError) {
+  if (UNLIKELY(new_status == kStatusError)) {
     CHECK_NE(GetStatus(), kStatusError)
         << "Attempt to set as erroneous an already erroneous class " << PrettyClass(this);
 
@@ -95,7 +95,8 @@
     // clear exception to call FindSystemClass
     self->ClearException();
     ClassLinker* class_linker = Runtime::Current()->GetClassLinker();
-    Class* eiie_class = class_linker->FindSystemClass("Ljava/lang/ExceptionInInitializerError;");
+    Class* eiie_class = class_linker->FindSystemClass(self,
+                                                      "Ljava/lang/ExceptionInInitializerError;");
     CHECK(!self->IsExceptionPending());
 
     // Only verification errors, not initialization problems, should set a verify error.