If a sample containing subdirs, a Cmake error will be raised, since the original code can only install FILES.

Feature allows to exclude CUDA or OpenCL optimizations at all even CUDA is used
on build. Exclusion of CUDA or OpenCL cut unwanted dependencies.

Env setup for testing package implemented using /etc/profile.d;
Variable with path for all native samples added;
Path for test binaries and test data updated.

HAVE_opencv_ocl implies HAVE_OPENCL, so checking for both is not
necessary.

The reasons for that are twofold:

1) LINK_PRIVATE is only available since CMake 2.8.7.
2) The way it was used generated a warning because of CMake policy CMP0023:

   http://www.cmake.org/cmake/help/v2.8.12/cmake.html#policy:CMP0023

Using LINK_INTERFACE_LIBRARIES actually causes another warning - this time
because of CMake policy CMP0022:

   http://www.cmake.org/cmake/help/v2.8.12/cmake.html#policy:CMP0022

I set the policy to OLD, because NEW means subtle changes when compiling
with CMake 2.8.12, and I don't want to research that this close to release.
:-)

I also removed the setting of CMP0003, because it's set by
cmake_minimal_version anyway.

Allow to build samples via OpenCV binaries from distribution package
(find_package with OpenCV_DIR).

This reverts commit 286244ef.

(cherry picked from commit aa96d8d0)

Also, removed needless check of BUILD_SHARED_LIBS in core; in that case,
only the current module's library type matters.