MFC r258821 - fix tcp simultaneous close

PR:             kern/99188


git-svn-id: svn+ssh://svn.freebsd.org/base/stable/6@260422 ccf9f872-aa2e-dd11-9fc8-001c23d0bc1f
Revert MFC of r258821 - it was already handled by MFC of r239672.

Pointy hat to: peter


git-svn-id: svn+ssh://svn.freebsd.org/base/stable/6@260438 ccf9f872-aa2e-dd11-9fc8-001c23d0bc1f