Support class lookup for InMemoryDexClassLoader

Setting up InMemoryDexClassLoader with 'null' as parent results in the
class loader not being able to load any boot classpath classes. This is
due to the fact that InMemoryDexClassLoader inherits class lookup from
BaseDexClassLoader which delegates it to ART, but ART rejects
InMemoryDexClassLoader as not supported.

Bug: 120603906
Bug: 120613979
Test: InMemoryDexClassLoaderTest
Change-Id: I3139b1bb343b5fc722bcf06f89a6f6a21a3c7c54
diff --git a/runtime/well_known_classes.h b/runtime/well_known_classes.h
index 0b7ed09..5178bf7 100644
--- a/runtime/well_known_classes.h
+++ b/runtime/well_known_classes.h
@@ -57,6 +57,7 @@
   static jclass dalvik_system_DexPathList;
   static jclass dalvik_system_DexPathList__Element;
   static jclass dalvik_system_EmulatedStackFrame;
+  static jclass dalvik_system_InMemoryDexClassLoader;
   static jclass dalvik_system_PathClassLoader;
   static jclass dalvik_system_VMRuntime;
   static jclass java_lang_annotation_Annotation__array;