Remove all uses of GTEST_DISALLOW_{MOVE_,}ASSIGN_.

None of these are strictly needed for correctness.
A large number of them (maybe all of them?) trigger `-Wdeprecated`
warnings on Clang trunk as soon as you try to use the implicitly
defaulted (but deprecated) copy constructor of a class that has
deleted its copy assignment operator.

By declaring a deleted copy assignment operator, the old code
also caused the move constructor and move assignment operator
to be non-declared. This means that the old code never got move
semantics -- "move-construction" would simply call the defaulted
(but deprecated) copy constructor instead. With the new code,
"move-construction" calls the defaulted move constructor, which
I believe is what we want to happen. So this is a runtime
performance optimization.

Unfortunately we can't yet physically remove the definitions
of these macros from gtest-port.h, because they are being used
by other code internally at Google (according to zhangxy988).
But no new uses should be added going forward.

googlemock/include/gmock/gmock-spec-builders.h

@@ -879,8 +879,6 @@ class GTEST_API_ ExpectationBase {
   Clause last_clause_;
   mutable bool action_count_checked_;  // Under mutex_.
   mutable Mutex mutex_;  // Protects action_count_checked_.
-
-  GTEST_DISALLOW_ASSIGN_(ExpectationBase);
 };  // class ExpectationBase
 
 // Impements an expectation for the given function type.
@@ -1295,8 +1293,6 @@ class MockSpec {
   internal::FunctionMocker<F>* const function_mocker_;
   // The argument matchers specified in the spec.
   ArgumentMatcherTuple matchers_;
-
-  GTEST_DISALLOW_ASSIGN_(MockSpec);
 };  // class MockSpec
 
 // Wrapper type for generically holding an ordinary value or lvalue reference.