sql_readline: "mal_export" -> "sql5_export"
sql_readline: "mal_export" -> "sql5_export"

This hopefully fixes a dllexport/dllimport conflict with Intel on Windows

Open issues:
============

- Why did only the Intel compiler complain, but not the Microsoft one?

- Why did the Intel compiler only issue a warning,
  but not (turn this into) an error?

zyzyis/monetdb,zyzyis/monetdb,zyzyis/monetdb,zyzyis/monetdb,zyzyis/monetdb,zyzyis/monetdb,zyzyis/monetdb,zyzyis/monetdb,zyzyis/monetdb,zyzyis/monetdb