man.sh: revert trapping SIGPIPE

PR: 279542
Fixes: 14a5c1068d37
Reported by: emaste
Reviewed by: imp, emaste, jilles
Pull Request: https://github.com/freebsd/freebsd-src/pull/1283

(cherry picked from commit a85d870007e7dd94242a2084dbb750438332ac1e)