Disable a couple of warnings generated by the GTest and GMock headers

Summary: As the comment says, this disables a couple of warnings related to exporting classes derived from stdlib classes that aren't explicitly exported.

Reviewed By: yfeldblum

Differential Revision: D4155978

fbshipit-source-id: 6e732b53c280a3bc3a39b2128cd577ba7cb70408

folly/portability/GMock.h

@@ -22,4 +22,12 @@
 #include <folly/portability/Unistd.h>
 #include <folly/portability/Windows.h>
 
+#include <folly/Portability.h>
+
+// Disable a couple of warnings due to GMock exporting classes
+// that derive from stdlib classes which aren't explicitly exported.
+FOLLY_PUSH_WARNING
+FOLLY_MSVC_DISABLE_WARNING(4251)
+FOLLY_MSVC_DISABLE_WARNING(4275)
 #include <gmock/gmock.h>
+FOLLY_POP_WARNING

folly/portability/GTest.h

@@ -22,4 +22,12 @@
 #include <folly/portability/Unistd.h>
 #include <folly/portability/Windows.h>
 
+#include <folly/Portability.h>
+
+// Disable a couple of warnings due to GTest exporting classes
+// that derive from stdlib classes which aren't explicitly exported.
+FOLLY_PUSH_WARNING
+FOLLY_MSVC_DISABLE_WARNING(4251)
+FOLLY_MSVC_DISABLE_WARNING(4275)
 #include <gtest/gtest.h>
+FOLLY_POP_WARNING