unixodbc vs iodbc

Index: src/pyodbcmodule.cpp
--- src/pyodbcmodule.cpp.orig
+++ src/pyodbcmodule.cpp
@@ -1102,7 +1102,9 @@ static const ConstantDef aConstants[] = {
     MAKECONST(SQL_CONVERT_DECIMAL),
     MAKECONST(SQL_CONVERT_DOUBLE),
     MAKECONST(SQL_CONVERT_FLOAT),
+#ifdef SQL_CONVERT_GUID
     MAKECONST(SQL_CONVERT_GUID),
+#endif
     MAKECONST(SQL_CONVERT_INTEGER),
     MAKECONST(SQL_CONVERT_INTERVAL_DAY_TIME),
     MAKECONST(SQL_CONVERT_INTERVAL_YEAR_MONTH),