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
_ZN7RBTrace10BufferSizeEv @ 1 NONAME
_ZN7RBTrace11RequestDataER14TRequestStatusi @ 2 NONAME
_ZN7RBTrace12ResizeBufferEi @ 3 NONAME
_ZN7RBTrace17CancelRequestDataEv @ 4 NONAME
_ZN7RBTrace4ModeEv @ 5 NONAME
_ZN7RBTrace4OpenEv @ 6 NONAME
_ZN7RBTrace5CloseEv @ 7 NONAME
_ZN7RBTrace5EmptyEv @ 8 NONAME
_ZN7RBTrace7GetDataERPh @ 9 NONAME
_ZN7RBTrace7SetModeEj @ 10 NONAME
_ZN7RBTrace8DataUsedEv @ 11 NONAME
_ZN7RBTrace9SetFilterEji @ 12 NONAME
_ZN7RBTrace10SetFilter2EPKmi @ 13 NONAME
_ZN7RBTrace10SetFilter2Ei @ 14 NONAME
_ZN7RBTrace10SetFilter2Emi @ 15 NONAME
_ZN7RBTrace7Filter2ERPmRi @ 16 NONAME
_ZN7RBTrace20SetTimestamp2EnabledEi @ 17 NONAME