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.

googletest/include/gtest/internal/gtest-internal.h

@@ -1120,8 +1120,6 @@ class NativeArray {
   const Element* array_;
   size_t size_;
   void (NativeArray::*clone_)(const Element*, size_t);
-
-  GTEST_DISALLOW_ASSIGN_(NativeArray);
 };
 
 // Backport of std::index_sequence.

googletest/include/gtest/internal/gtest-port.h

@@ -682,7 +682,7 @@ typedef struct _RTL_CRITICAL_SECTION GTEST_CRITICAL_SECTION;
 // This should be used in the private: declarations for a class.
 #define GTEST_DISALLOW_COPY_AND_ASSIGN_(type) \
   type(type const &) = delete; \
-  GTEST_DISALLOW_ASSIGN_(type)
+  type& operator=(type const &) = delete
 
 // A macro to disallow move operator=
 // This should be used in the private: declarations for a class.
@@ -693,7 +693,7 @@ typedef struct _RTL_CRITICAL_SECTION GTEST_CRITICAL_SECTION;
 // This should be used in the private: declarations for a class.
 #define GTEST_DISALLOW_MOVE_AND_ASSIGN_(type) \
   type(type &&) noexcept = delete; \
-  GTEST_DISALLOW_MOVE_ASSIGN_(type)
+  type& operator=(type &&) noexcept = delete
 
 // Tell the compiler to warn about unused return values for functions declared
 // with this macro.  The macro should be used on function declarations
@@ -920,8 +920,6 @@ class GTEST_API_ RE {
   const char* full_pattern_;  // For FullMatch();
 
 # endif
-
-  GTEST_DISALLOW_ASSIGN_(RE);
 };
 
 #endif  // GTEST_USES_PCRE

googletest/test/googletest-port-test.cc

@@ -1180,8 +1180,6 @@ class DestructorTracker {
     return DestructorCall::List().size() - 1;
   }
   const size_t index_;
-
-  GTEST_DISALLOW_ASSIGN_(DestructorTracker);
 };
 
 typedef ThreadLocal<DestructorTracker>* ThreadParam;