message: regalloc: Don't copy DefsEnvironment unnecessarily
diff: @@ -101,7 +101,7 @@ class DefsEnvironment final : public AbstractDomainReverseAdaptor<
  return unwrap().get(reg);
  }
  - DefsEnvironment set(reg_t reg, const DefsDomain& value) {
  + DefsEnvironment& set(reg_t reg, const DefsDomain& value) {
  unwrap().set(reg, value);
  return *this;
  }
  