1. Let btvRegWeights to be constant per `process` call.
2. Let Farneback to be the default optical flow method.
3. Fix a timing method bug for ocl path.
4. Remove useless finish operation in farneback
5. Refactor buffer usage.
ocl: show diff
Merge pull request #1683 from alalek:ocl_restore_showdiff
enabled ocl::bilateralFilter ROI testing
Removed a stray comma in the Android toolchain file.

It was actually acting as an additional argument, breaking the error message.
Replaced our usage of LINK_PRIVATE with that of LINK_INTERFACE_LIBRARIES.

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.
fixed separable filter extrapolation
cmake: fix android installation for different NDK ABIs
fixed extrapolation in ocl::adaptiveBilateralFilter
Merge pull request #1680 from alalek:cmake_fix_android_builds
fixing typo
Fixed Android SDK build - again.
Merge pull request #1690 from SpecLad:cmake-2.8.12
Merge pull request #1693 from ilya-lavrenov:ocl_adaptiveBilateralFilter
Merge pull request #1694 from apavlenko:fix_typo
Merge pull request #1692 from ilya-lavrenov:ocl_separableFilter
Merge pull request #1689 from ilya-lavrenov:ocl_bilateralFilter
Merge pull request #1655 from pengx17:2.4_opt_superres_ocl
Merge pull request #1697 from SpecLad:sdk-redux