Enhance the base/rom extension to generate the symbol file of the rom built. The symbol file is placed in epoc32/rom/<baseport_name>, along with the rom log and final oby file.

EXPORTS
	Function3__Fv @ 1 NONAME
	Function4__Fv @ 2 NONAME
	GetDll3Data__Fv @ 3 NONAME
	SetDll3Data__Fi @ 4 NONAME