Fix static bitcoin-qt build for x86_64-linux-gnu arch.
Fix static bitcoin-qt build for x86_64-linux-gnu arch.

The actual "depends" machinery does not produce bitcoin-qt
while compiling static buids (i.e. `make -C depends
HOST=x86_64-linux-gnu). This is a temporary fix that let us
produce the gitian builds (who depends on the static build)
without wasting time. As soon as we have the release out
of the door we are going to commit a proper fix.

The problem is that Qt binaries (uic, lrelease, /qdbuscpp2xml and
qdbusxml2cpp) are installed under depends/x86_64-linux-gnu/bin
rather than depends/x86_64-linux-gnu/native/bin.

Justaphf/BitcoinUnlimited,cddjr/BitcoinUnlimited,BitcoinUnlimited/BitcoinUnlimited,AllanDoensen/BitcoinUnlimited,AllanDoensen/BitcoinUnlimited,marcusdiaz/BitcoinUnlimited,marcusdiaz/BitcoinUnlimited,Justaphf/BitcoinUnlimited,ftrader-bitcoinunlimited/hardfork_prototype_1_mvf-bu,krzysztofwos/BitcoinUnlimited,AllanDoensen/BitcoinUnlimited,ftrader-bitcoinunlimited/hardfork_prototype_1_mvf-bu,ftrader-bitcoinunlimited/hardfork_prototype_1_mvf-bu,Bitcoin-com/BUcash,krzysztofwos/BitcoinUnlimited,Justaphf/BitcoinUnlimited,marcusdiaz/BitcoinUnlimited,arruah/ensocoin,krzysztofwos/BitcoinUnlimited,AllanDoensen/BitcoinUnlimited,BTCfork/hardfork_prototype_1_mvf-bu,arruah/ensocoin,BitcoinUnlimited/BitcoinUnlimited,BTCfork/hardfork_prototype_1_mvf-bu,Bitcoin-com/BUcash,arruah/ensocoin,Justaphf/BitcoinUnlimited,ftrader-bitcoinunlimited/hardfork_prototype_1_mvf-bu,cddjr/BitcoinUnlimited,Justaphf/BitcoinUnlimited,Bitcoin-com/BUcash,ftrader-bitcoinunlimited/hardfork_prototype_1_mvf-bu,marcusdiaz/BitcoinUnlimited,marcusdiaz/BitcoinUnlimited,AllanDoensen/BitcoinUnlimited,arruah/ensocoin,BitcoinUnlimited/BitcoinUnlimited,BTCfork/hardfork_prototype_1_mvf-bu,BitcoinUnlimited/BitcoinUnlimited,BitcoinUnlimited/BitcoinUnlimited,krzysztofwos/BitcoinUnlimited,BTCfork/hardfork_prototype_1_mvf-bu,cddjr/BitcoinUnlimited,cddjr/BitcoinUnlimited,cddjr/BitcoinUnlimited,Bitcoin-com/BUcash,marcusdiaz/BitcoinUnlimited,krzysztofwos/BitcoinUnlimited,ftrader-bitcoinunlimited/hardfork_prototype_1_mvf-bu,Justaphf/BitcoinUnlimited,BTCfork/hardfork_prototype_1_mvf-bu,arruah/ensocoin,arruah/ensocoin,BitcoinUnlimited/BitcoinUnlimited,AllanDoensen/BitcoinUnlimited,Bitcoin-com/BUcash,cddjr/BitcoinUnlimited,BTCfork/hardfork_prototype_1_mvf-bu,Bitcoin-com/BUcash,krzysztofwos/BitcoinUnlimited