[mythtv] mythplugins from SVN branch release-0-18-fixes rev 8482 does not build

[Paul Bender]

mythplugins from SVN branch release-0-18-fixes rev 8482 does not build.

Recently, the mythtv version on this branch was bumped from 0.18.1 to 
0.18.2, but settings.pro for mythplugins still references version 
0.18.1. As a result, mythbrowser and mtd will not build, because they 
explicitly link against libmyth-0.18.1, which does not exist.