qbs project: Fix another duplicate dependency

Change-Id: Id50643364b174e150666f4591fa6eaf91144336b
Reviewed-by: Joerg Bornemann <joerg.bornemann@digia.com>
qbs project: Do not build valgrind test apps on Windows

Valgrind doesn't work on Windows, and the compiler flags for those test
apps are incompatible with MSVC

Change-Id: I9c17c29759d18434ef4a14cc57bcfde8405d770f
Reviewed-by: Joerg Bornemann <joerg.bornemann@digia.com>