This retains the desirable quality of not including paths to CUDA libraries
from the build system into the config files, and has two major advantages:
* It removes the need to use link_directories, which doesn't guarantee that
the libraries from the supplied directory will be used (there may be
libraries with the same names earlier in the search path).
* It removes the need to put -L entries into OPENCV_LINKER_LIBS. This variable
is used with target_link_libraries, where such entries are treated as linker
flags, so doing this is unportable. I remove the support for -L entries
from OpenCVGenPkgconfig.cmake, as well, to discourage adding them in the
future.
6e121b2e29