Fix visibility of g_linked_ptr_mutex on Windows

Reverts some changes in b8ed00bd64

modules/ts/include/opencv2/ts.hpp

@@ -4,6 +4,14 @@
 #include "opencv2/core/cvdef.h"
 #include <stdarg.h> // for va_list
 
+#include "cvconfig.h"
+
+#ifndef GTEST_CREATE_SHARED_LIBRARY
+#ifdef BUILD_SHARED_LIBS
+#define GTEST_LINKED_AS_SHARED_LIBRARY 1
+#endif
+#endif
+
 #ifdef _MSC_VER
 #pragma warning( disable: 4127 )
 #endif