decrease input size for several gpu tests to fix "timed out" error:

* BruteForceNonLocalMeans
* OpticalFlowBM
Fixed Cl.exe hang for VS2008 x64 with Eigen::exp() function
Merge pull request #2309 from Nerei:fixed_cl_exe_hang_with_eigen
Merge pull request #2308 from jet47:gpu-tests-timeout