1, Add comments for include<algorithm> we added for min/max on VS2013. 2, Add…

1, Add comments for include<algorithm> we added for min/max on VS2013. 2, Add #if/#endif to wrap #undef

src/google/protobuf/repeated_field.h

@@ -47,6 +47,7 @@
 #define GOOGLE_PROTOBUF_REPEATED_FIELD_H__
 
 #ifdef _MSC_VER
+// This is required for min/max on VS2013 only.
 #include <algorithm>
 #endif
 

src/google/protobuf/stubs/atomicops.h

@@ -120,7 +120,9 @@ Atomic32 Release_CompareAndSwap(volatile Atomic32* ptr,
                                 Atomic32 old_value,
                                 Atomic32 new_value);
 
+#if defined(__MINGW32__) && defined(MemoryBarrier)
 #undef MemoryBarrier
+#endif
 void MemoryBarrier();
 void NoBarrier_Store(volatile Atomic32* ptr, Atomic32 value);
 void Acquire_Store(volatile Atomic32* ptr, Atomic32 value);

src/google/protobuf/wire_format_lite_inl.h

@@ -37,6 +37,7 @@
 #define GOOGLE_PROTOBUF_WIRE_FORMAT_LITE_INL_H__
 
 #ifdef _MSC_VER
+// This is required for min/max on VS2013 only.
 #include <algorithm>
 #endif