Remove .pm from the module name in the POD

In OpenBSD we use the NAME of the module to create man page references. The .pm on the name means we have to special case this module.

https://github.com/afresh1/OpenBSD-perl/blob/5_19/patches/GOOD/UPSTREAM/cpan_NEXT_lib_NEXT.pm.patch
http://www.openbsd.org/cgi-bin/cvsweb/src/gnu/usr.bin/perl/cpan/NEXT/lib/NEXT.pm.diff?r1=1.1;r2=1.2;f=h