qdoc: Exclude qdoc src dirs when generating Qt 5 docs
qdoc: Exclude qdoc src dirs when generating Qt 5 docs

The qdoc src directories should be excluded from the input.

Task Nr: QTBUG-26493

Change-Id: I2eba116648de3ef07a37ec4dfe80f82d95c19288
Reviewed-by: Casper van Donderen <808524cef5c654648bea2a2b954f3b3445ed083c@nokia.com>

kobolabs/qtdoc,kobolabs/qtdoc,kobolabs/qtdoc,kobolabs/qtdoc