expose dwarf_regno as a platform specific function
Fix issue 9777 Wrong code when calling final interface methods

Can't use DotTypeExp when converting to the interface as the
pointer needs to be adjusted. Use CastExp instead.
Merge pull request #1776 from braddr/dwarf

expose dwarf_regno as a platform specific function
Merge pull request #1781 from jpf91/fix9777

Fix issue 9777 Wrong code when calling final interface methods