Refactor.
* gettext-tools/src/read-catalog-abstract.h
(abstract_catalog_reader_class_ty::comment_filepos): Change parameter names.
(po_callback_comment_filepos): Likewise.
* gettext-tools/src/read-catalog-abstract.c (call_comment_filepos,
po_callback_comment_filepos): Likewise.
* gettext-tools/src/read-catalog.h (default_comment_filepos): Likewise.
* gettext-tools/src/read-catalog.c (default_comment_filepos): Likewise.
