cffi/c2ffi: fix the emission of the export statement.
cffi/c2ffi: fix the emission of the export statement.

 - make sure we don't try to emit a base-string.
 - add an unrelated comment without semantic change.

dkochmanski/cffi,cffi/cffi,cffi/cffi,3b/cffi,3b/cffi,attila-lendvai/cffi,cffi/cffi,dkochmanski/cffi,stassats/cffi,mcna/cffi,3b/cffi,stassats/cffi,stassats/cffi,dkochmanski/cffi,mcna/cffi,attila-lendvai/cffi