Revert "Revert "ART: Mterp for arm64""

Looks like some of our assemblers disagree on valid arm64 assembly syntax
Force use of clang for art runtime.  In a subsequent CL, will use form
that both gcc and clang accept.

This reverts commit 43f3fb960bce978df699c8a68a972be2a0d0d221.

Change-Id: Ice83072171ab502c43d492e2238b446c4814ea67
diff --git a/runtime/interpreter/interpreter.cc b/runtime/interpreter/interpreter.cc
index e93bbdb..3eff7fc 100644
--- a/runtime/interpreter/interpreter.cc
+++ b/runtime/interpreter/interpreter.cc
@@ -240,7 +240,7 @@
 }
 
 #if !defined(__clang__)
-#if (defined(__arm__) || defined(__i386__))
+#if (defined(__arm__) || defined(__i386__) || defined(__aarch64__))
 // TODO: remove when all targets implemented.
 static constexpr InterpreterImplKind kInterpreterImplKind = kMterpImplKind;
 #else
@@ -248,7 +248,7 @@
 #endif
 #else
 // Clang 3.4 fails to build the goto interpreter implementation.
-#if (defined(__arm__) || defined(__i386__))
+#if (defined(__arm__) || defined(__i386__) || defined(__aarch64__))
 static constexpr InterpreterImplKind kInterpreterImplKind = kMterpImplKind;
 #else
 static constexpr InterpreterImplKind kInterpreterImplKind = kSwitchImplKind;