reverted QTKit-related commits

This reverts commit 956813bdd5e7940d33084b2c42d60500d3e651dd.
Revert "quicktime and clang"

This reverts commit 06a8a032a39a581368e116d78cf26e87e933e0a9.
Revert "Introduced HAVE_QTKIT to allow using QTKit"

This reverts commit b4c198986070141635c09217b55f6c41bd1765e0.
Revert "Hard-coding to make qtkit appear again"

This reverts commit 6751403646825552f8249be3d659d27c7404fc06.