Qbs: Update to latest Qbs API

This also fixes parsing when environment variables are read in
qbs files.

Change-Id: Iad78296986f8700272d6027d2ffa645d4207bdef
Reviewed-by: Tobias Hunger <tobias.hunger@digia.com>
Debugger: Suppress GDB's memory-changed notification

Change-Id: I266b1cef33e53250da79fac0473c3d45eb740ddb
Reviewed-by: hjk <hjk121@nokiamail.com>