Removed call to `TryCreateDirectory` from `GetDefaultDataDir` in `src/util.cpp`.
Removed call to `TryCreateDirectory` from `GetDefaultDataDir` in `src/util.cpp`.

See https://github.com/bitcoin/bitcoin/issues/7845#issuecomment-207684728.
Also refactored `GetDefaultDataDir` function to return path for Mac in one expression.

Github-Pull: #7850
Rebased-From: 41dbc4849e0bf14eef98962b0f0bddcde0bb3014

deadalnix/bitcoin,deadalnix/bitcoin,zander/bitcoinclassic,deadalnix/bitcoin,adpg211/bitcoin-master,zander/bitcoinclassic,deadalnix/bitcoin,adpg211/bitcoin-master,bitcoinclassic/bitcoinclassic,zander/bitcoinclassic,zander/bitcoinclassic,deadalnix/bitcoin,adpg211/bitcoin-master,zander/bitcoinclassic,bitcoinclassic/bitcoinclassic,bitcoinclassic/bitcoinclassic,zander/bitcoinclassic,bitcoinclassic/bitcoinclassic,bitcoinclassic/bitcoinclassic,bitcoinclassic/bitcoinclassic,deadalnix/bitcoin,adpg211/bitcoin-master,adpg211/bitcoin-master,adpg211/bitcoin-master