[build] .gitignore: add QT Creator artifacts

Author: Sjors

.gitignore

@@ -44,6 +44,12 @@ src/qt/forms/ui_*.h
 
 src/qt/test/moc*.cpp
 
+src/qt/bitcoin-qt.config
+src/qt/bitcoin-qt.creator
+src/qt/bitcoin-qt.creator.user
+src/qt/bitcoin-qt.files
+src/qt/bitcoin-qt.includes
+
 .deps
 .dirstamp
 .libs