Add AbstractMethod, Constructor, Method

Moves functionality to ART from libcore. Precursor to moving
ArtMethods to native. Mostly performance improvements.

N5 perf before (irrelevant results removed):
            Class_getConstructor  962.87 ===========
         Class_getDeclaredMethod 2394.37 ============================
                 Class_getMethod 2509.20 ==============================
               Class_newInstance 1999.81 =======================
                  Method_invokeI 1439.02 =================
          Method_invokePreBoxedI 1415.82 ================
            Method_invokeStaticI 1456.24 =================
    Method_invokeStaticPreBoxedI 1427.32 =================
            Method_invokeStaticV  814.47 =========
                  Method_invokeV  816.56 =========
After:
                       benchmark      ns linear runtime
            Class_getConstructor 1302.04 ================
         Class_getDeclaredMethod 1459.01 ==================
                 Class_getMethod 1560.40 ===================
               Class_newInstance 2029.94 =========================
                  Method_invokeI 1312.89 ================
          Method_invokePreBoxedI 1255.01 ===============
            Method_invokeStaticI 1289.13 ===============
    Method_invokeStaticPreBoxedI 1196.52 ==============
            Method_invokeStaticV  790.82 =========
                  Method_invokeV  791.73 =========

Performance improvements are more than just fixing regressions introduced
in: http://android-review.googlesource.com/#/c/146069/

Bug: 19264997

Change-Id: Ife79c469fdb09f30e3aefcfc3e0ce5ed32303fce
diff --git a/runtime/mirror/class.h b/runtime/mirror/class.h
index 20f2387..5005346 100644
--- a/runtime/mirror/class.h
+++ b/runtime/mirror/class.h
@@ -47,6 +47,7 @@
 
 class ArtMethod;
 class ClassLoader;
+class Constructor;
 class DexCache;
 class IfTable;
 
@@ -1052,6 +1053,11 @@
     return OFFSET_OF_OBJECT_MEMBER(Class, dex_cache_strings_);
   }
 
+  // May cause thread suspension due to EqualParameters.
+  mirror::ArtMethod* GetDeclaredConstructor(
+      Thread* self, Handle<mirror::ObjectArray<mirror::Class>> args)
+      SHARED_LOCKS_REQUIRED(Locks::mutator_lock_);
+
   // Used to initialize a class in the allocation code path to ensure it is guarded by a StoreStore
   // fence.
   class InitializeClassVisitor {