Free properly all metadata extracted from PDF files.
Free properly all metadata extracted from PDF files.

both tracker_coalesce() and write_pdf_data() free the used values,
so only keywords in the XMP case must be freed, since it isn't used.

hoheinzollern/tracker,hoheinzollern/tracker,hoheinzollern/tracker,outofbits/tracker,outofbits/tracker,outofbits/tracker,outofbits/tracker,hoheinzollern/tracker,outofbits/tracker,hoheinzollern/tracker,outofbits/tracker,hoheinzollern/tracker,hoheinzollern/tracker,outofbits/tracker