The opencv element includes were full of duplicates and uneeded headers.
For example a few elements that stopped using gstcvopencvutils still
included that header file.
The cascade classifier changes its structure on new version of OpenCV 2.4.11.
It is need to migrate to C++ to utilize the new load method of OpenCV which
allows to load the old and new classifiers.
https://bugzilla.gnome.org/show_bug.cgi?id=752528
If old opencv1-style legacy include directory is available,
this change becomes purely cosmetic (maybe will compile a bit faster).
It becomes an FTBFS fix when opencv1-style include directory is missing
(possibly because opencv package maintainer decided not to pack it).
https://bugzilla.gnome.org/show_bug.cgi?id=747705
