- Skip dummy/invalid export symbols.
- Make the export ordinal of export symbols visible when dumping the
symtab.
- Stop setting the 'Debug' flag and set the 'External' flag instead to
better match the meaning of export symbols.
- Try to guess the type (code vs data) of the symbol from section flags.
Reviewed By: labath
Differential Revision: https://reviews.llvm.org/D134265