fixed home variable

Hi guys, we ran into an error while running rpmbuild to create an rpm from the nagios-plugins tarball.  It looks like the reference to %{nshome} is a syntax error, as there's no other references to that name anywhere in the spec file.  We changed it to %{nphome} which is defined earlier in the spec and everything works now.

Our rpmbuild box is running centos 6.5 x64 in case it matters.  Thanks!