The HAVE_DOC_GENERATOR variable was always true.

Absolute destinations are not necessary, and prevent CPack from working.

use `bash` shell instead of `sh`, since on Ubuntu `sh` by default is `dash`,
and `dash` doesn't support `PIPESTATUS` feature used in this sctipt

Modified resetCvImage() in cap_ximea.cpp, so that the IplImage* frame is also updated after the resolution has changed via set(CV_CAP_PROP_FRAME_WIDTH, value)/set(CV_CAP_PROP_XI_DOWNSAMPLING, value)

(cherry picked from commit 8910508b)