MFC r298753:

MFC r298753:

Fix va_list handling

- Add missing va_end's after corresponding va_start's to cleanup state
- Eliminate questionable bzero'ing of va_list passed in to
  do_buff_decode(..) and do_encode(..) from buff_{de,en}code_visit(..)
  and csio_{de,en}code_visit(..). Make va_list a pointer instead and
  pass NULL into the underlying functions to handler this in a portable
  way.
- Do some minor style(9) clean up in affected functions.

CID: 1018500-1018503

git-svn-id: svn://svn.freebsd.org/base/stable/10@299024 ccf9f872-aa2e-dd11-9fc8-001c23d0bc1f