AArch64: Add arm64 runtime support.

Adds support for arm64 to ART. Assembler stubs are sufficient for
down calls into interpreter. JNI compiler and generics are not finished.

Basic Generic JNI functionality.

Change-Id: I4a07c79d1e037b9f5746673480e32cf456867b82
diff --git a/runtime/mirror/art_method.cc b/runtime/mirror/art_method.cc
index e8a0891..7814f36 100644
--- a/runtime/mirror/art_method.cc
+++ b/runtime/mirror/art_method.cc
@@ -37,7 +37,7 @@
 extern "C" void art_portable_invoke_stub(ArtMethod*, uint32_t*, uint32_t, Thread*, JValue*, char);
 extern "C" void art_quick_invoke_stub(ArtMethod*, uint32_t*, uint32_t, Thread*, JValue*,
                                       const char*);
-#ifdef __x86_64__
+#ifdef __LP64__
 extern "C" void art_quick_invoke_static_stub(ArtMethod*, uint32_t*, uint32_t, Thread*, JValue*,
                                              const char*);
 #endif
@@ -282,7 +282,7 @@
                                                   : GetEntryPointFromPortableCompiledCode());
       }
       if (!IsPortableCompiled()) {
-#ifdef __x86_64__
+#ifdef __LP64__
         if (!IsStatic()) {
           (*art_quick_invoke_stub)(this, args, args_size, self, result, shorty);
         } else {