Remove check for NSPR in configure.ac
Remove check for NSPR in configure.ac

The firefox/mozilla-plugin pkgconfig files already have a dependancy
on the nspr package. Thus there is no need for an explicit NSPR check
in gtk-vnc.

* configure.ac: Remove redundant check for NSPR

jwendell/gtk-vnc,jwendell/gtk-vnc,jwendell/gtk-vnc,jwendell/gtk-vnc,jwendell/gtk-vnc