sh: Fix corruption of CTL* bytes in positional parameters in redirection.

EXP_REDIR was not being checked for while expanding positional parameters in
redirection, so CTL* bytes were not being prefixed where they should be.

MFC after:	1 week


git-svn-id: svn+ssh://svn.freebsd.org/base/head@273920 ccf9f872-aa2e-dd11-9fc8-001c23d0bc1f