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/elf_builder.h b/compiler/elf_builder.h
index 273b62d..94268de 100644
--- a/compiler/elf_builder.h
+++ b/compiler/elf_builder.h
@@ -1108,6 +1108,14 @@
                                EF_MIPS_ARCH_32R2);
         break;
       }
+      case kMips64: {
+        elf_header_.e_machine = EM_MIPS;
+        elf_header_.e_flags = (EF_MIPS_NOREORDER |
+                               EF_MIPS_PIC       |
+                               EF_MIPS_CPIC      |
+                               EF_MIPS_ARCH_64R6);
+        break;
+      }
       default: {
         fatal_error_ = true;
         LOG(FATAL) << "Unknown instruction set: " << isa;