ART: Allow to compile interpret-only mips64 files

Include enough infrastructure to allow cross-compiling for mips64,
interpret-only. This includes the instruction-set-features, frame
size info and utils assembler.

Also add a disassembler for oatdump, and support in patchoat.

Note: the runtime cannot run mips64, yet.

Change-Id: Id106581fa76b478984741c62a8a03be0f370d992
diff --git a/compiler/utils/assembler.h b/compiler/utils/assembler.h
index 134dda4..923ecdb 100644
--- a/compiler/utils/assembler.h
+++ b/compiler/utils/assembler.h
@@ -47,6 +47,9 @@
 namespace mips {
   class MipsAssembler;
 }
+namespace mips64 {
+  class Mips64Assembler;
+}
 namespace x86 {
   class X86Assembler;
 }
@@ -120,6 +123,7 @@
   friend class arm::Thumb2Assembler;
   friend class arm64::Arm64Assembler;
   friend class mips::MipsAssembler;
+  friend class mips64::Mips64Assembler;
   friend class x86::X86Assembler;
   friend class x86_64::X86_64Assembler;