This is part of clean-up for a new Clang warning that we'd like to
enable. This patch addresses all warnings from V8 that I saw in a full debug
build of Chromium on Linux.

../../v8/src/reloc-info.h:405:18: warning: explicitly defaulted move assignment
operator is implicitly deleted [-Wdefaulted-function-deleted]
  RelocIterator& operator=(RelocIterator&&) = default;
                 ^
../../v8/src/reloc-info.h:447:13: note: move assignment operator of
'RelocIterator' is implicitly deleted because field 'mode_mask_' is of
const-qualified type 'const int'
  const int mode_mask_;
            ^

../../v8/src/wasm/baseline/liftoff-compiler.cc:111:36: warning: explicitly
defaulted move constructor is implicitly deleted [-Wdefaulted-function-deleted]
  MOVE_ONLY_NO_DEFAULT_CONSTRUCTOR(LiftoffCompiler);
                                   ^
../../v8/src/wasm/baseline/liftoff-compiler.cc:1834:20: note: move constructor
of 'LiftoffCompiler' is implicitly deleted because field 'asm_' has a deleted
move constructor
  LiftoffAssembler asm_;
                   ^

../../v8/src/wasm/wasm-debug.cc:95:3: warning: explicitly defaulted move
assignment operator is implicitly deleted [-Wdefaulted-function-deleted]
  MOVE_ONLY_NO_DEFAULT_CONSTRUCTOR(InterpreterHandle);
  ^
../../v8/src/wasm/wasm-debug.cc:98:19: note: move assignment operator of
'InterpreterHandle' is implicitly deleted because field 'interpreter_' has a
deleted move assignment operator
  WasmInterpreter interpreter_;
                  ^
../../v8/src/wasm/wasm-interpreter.h:211:35: note: copy assignment operator of
'WasmInterpreter' is implicitly deleted because field 'internals_' is of
const-qualified type 'v8::internal::wasm::WasmInterpreterInternals *const'
  WasmInterpreterInternals* const internals_;
                                  ^

Bug: chromium:890307
Change-Id: Idfc5827f24821212081a006c4329c466c4576bcc
Reviewed-on: https://chromium-review.googlesource.com/c/1256863
Commit-Queue: Bill Budge <bbudge@chromium.org>
Reviewed-by: Bill Budge <bbudge@chromium.org>
Cr-Commit-Position: refs/heads/master@{#56351}