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/elf_utils.h b/runtime/elf_utils.h
index acc6f46..f3ec713 100644
--- a/runtime/elf_utils.h
+++ b/runtime/elf_utils.h
@@ -33,6 +33,8 @@
 #define EF_MIPS_CPIC 4
 #define STV_DEFAULT 0
 
+#define EM_AARCH64 183
+
 #define DT_BIND_NOW 24
 #define DT_INIT_ARRAY 25
 #define DT_FINI_ARRAY 26