x11-toolkit/ruby-qt2 port

[Sergey Matveychuk]

When I'v tested a patch for bsd.ports.mk I'v found out a defect in 
ruby-qt2 port.

You can have two versions of this port: ruby-qt2 and ruby_r-qt2 but one 
file (RUBY_SITELIBDIR/qt2.rb) is common. So when you deinstall one of 
them you lose it for other one.

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Sem.