[mythtv] 0.21-fixes Windows port plugins installation failed

[Jeff Lu]

> I notices that there isn't path C:/mythtv/build/bin/mythtv/plugins.
> Path C:\mythtv\build\bin\sqldrivers is the deepest and no other
> subdirs in C:\mythtv\build\bin.

A buggy qmake file in trunk causes win32 plugins to install to the wrong directory.  But apparently someone changed the packager script check that wrong location instead of fixing the qmake file in trunk.

As you're building 0.21, the plugins are in the correct location.  You should edit your win32_packager.pl to check c:/mythtv/build/lib/mythtv/plugins