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-generated-actions.h

@@ -435,16 +435,12 @@
       template <GMOCK_ACTION_TEMPLATE_ARGS_NAMES_>\
       return_type gmock_PerformImpl(GMOCK_ACTION_ARG_TYPES_AND_NAMES_) const;\
       GMOCK_INTERNAL_DEFN_##value_params\
-     private:\
-      GTEST_DISALLOW_ASSIGN_(gmock_Impl);\
     };\
     template <typename F> operator ::testing::Action<F>() const {\
       return ::testing::Action<F>(\
           new gmock_Impl<F>(GMOCK_INTERNAL_LIST_##value_params));\
     }\
     GMOCK_INTERNAL_DEFN_##value_params\
-   private:\
-    GTEST_DISALLOW_ASSIGN_(GMOCK_ACTION_CLASS_(name, value_params));\
   };\
   template <GMOCK_INTERNAL_DECL_##template_params\
             GMOCK_INTERNAL_DECL_TYPE_##value_params>\