Raise and clean up _WIN32_WINNT constant

src/database/database-postgresql.cpp

@@ -23,10 +23,6 @@ with this program; if not, write to the Free Software Foundation, Inc.,
 #include "database-postgresql.h"
 
 #ifdef _WIN32
-        // Without this some of the network functions are not found on mingw
-        #ifndef _WIN32_WINNT
-                #define _WIN32_WINNT 0x0501
-        #endif
         #include <windows.h>
         #include <winsock2.h>
 #else