Revert "qt: add QT_COORD_TYPE to double option"

This reverts commit 7619aba4.

This change causes a number of build issues with poppler / pinentry /
python-pyqt and Qt itself on various architectures, so lets revert it for
now and rework it for the 2015.08 cycle.

Signed-off-by: Peter Korsgaard <peter@korsgaard.com>