Suppress warnings from manpath.
Suppress warnings from manpath.

After installing perlbrew, a warning was printed each time I opened a
new terminal. I traced it to manpath. When manpath is invoked, it prints
a warning message if $MANPATH is already set. This patch suppresses that
warning.

josl/App-perlbrew,calid/App-perlbrew,rafl/App-perlbrew,rafl/App-perlbrew,dagolden/App-perlbrew,Asuza/App-perlbrew,josl/App-perlbrew,josl/App-perlbrew,calid/App-perlbrew,Asuza/App-perlbrew,ptolemarch/App-perlbrew,ptolemarch/App-perlbrew,dagolden/App-perlbrew,rafl/App-perlbrew,Asuza/App-perlbrew,ptolemarch/App-perlbrew