Fix wxGetWinVersion() for Windows 10

Check for Windows 10 was implemented as check for version 6.4 but the final version of Windows 10 actually returns 10.0.

src/msw/utils.cpp

@@ -1496,7 +1496,6 @@ wxWinVersion wxGetWinVersion()
                             return wxWinVersion_8;
 
                         case 3:
-                        case 4:
                             // For now, map to wxWinVersion_8. In case program
                             // does not have a manifest indicating 8.1 or 10
                             // support, Windows already performs this mapping
@@ -1504,6 +1503,9 @@ wxWinVersion wxGetWinVersion()
                             return wxWinVersion_8;
                     }
                     break;
+
+                case 10:
+                    return wxWinVersion_8;
             }
         default:
             // Do nothing just to silence GCC warning