Be explicit with OpenCV components

Review Request #119201 - Created July 9, 2014 and submitted - Latest diff uploaded

Vadim Zhukov

This makes Digikam being explicit in what OpenCV components are needed. This results in less number of libraries to be linked to. As a result, Digikam starts a bit faster, eats a bit less memory and makes downstream (packagers) a bit more happy. Also it helps in cases when OpenCV package is split (for example, with non-free components separated) - without explicit mentioning of what components are needed, it's not clear will Digikam link to some components or not.

OpenBSD/i386-CURRENT, KDE 4.11.5+Digikam 3.x and KDE 4.13.2+Digikam 4.x