Omit autotests from Qt source packages

The autotests should probably be omitted from the source packages, as was done for Qt 4. The autotests are mainly useful for people developing Qt itself (and will use the git repo's for that purpose), rather than for people developing applications with Qt. Omitting the tests will reduce the size of the compressed .tar.gz package by around 25Mb and the uncompressed package by around 190Mb.

It may be necessary to make some minor modifications to some .pro files to ensure that Qt builds successfully without the autotests being present in the tree.