* module/rnrs/bytevectors.scm:
* module/rnrs/io/ports.scm: Add #:version (6) to these modules.
* module/6/rnrs.scm: Add versions to the import specs for bytevectors
and ports.
because of conflict between `syntax-case' transformer binding and
`(rnrs syntax-case)' hierarchical namespace module binding.)
* module/6/rnrs.scm: New file.
* module/Makefile.am: Add 6/rnrs.scm to RNRS_SOURCES.