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
_ZN11TAdcChannel4ReadEPi @ 1 NONAME ; TAdcChannel::Read(int*)
_ZN11TAdcChannel8PreambleEv @ 2 NONAME ; TAdcChannel::Preamble()
_ZN11TAdcChannel9PostambleEv @ 3 NONAME ; TAdcChannel::Postamble()
_ZTV11TAdcChannel @ 4 NONAME ; vtable for TAdcChannel
_ZN11TAdcChannelC2Ei @ 5 NONAME ; TAdcChannel::TAdcChannel(int)
_ZN4DAdc14SetMinPriorityEii @ 6 NONAME ; DAdc::SetMinPriority(int, int)
_ZTI11TAdcChannel @ 7 NONAME ; typeinfo for TAdcChannel