'master'-like Haar perf test
refactoring the test as it should be in 2.4
Added throwing exception when saving untrained SVM model
adding `finish()` to flush CL queue, renaming the test to match 'master' branch
Fix the following error for ocl::getOpenCLPlatforms() on Ubuntu 12.04 with gcc 4.8
OpenCV Error: Unknown error code -6 (OpenCL function is not available: [clGetPlatformIDs]) in opencl_check_fn, file /home/ahb/software/opencv/modules/ocl/src/cl_runtime/cl_runtime.cpp, line 83

The issue results from modules/ocl/src/cl_runtime/cl_runtime.cpp checking for
"linux" instead of "__linux__" (cp.  http://sourceforge.net/p/predef/wiki/OperatingSystems/)

Adjust all other occurrences of "defined(linux)" as well.
Merge pull request #2133 from apavlenko:2.4-perf_haar
Merge pull request #2145 from andreasBihlmaier:2.4
Fixed cvtColor alpha channel docs
Merge pull request #2143 from Daniil-Osokin:fix_docs_cvt_color_alpha_channel
Revert "fixed bug #3319"

See 092f916 for explanation.

This reverts commit 4f9c081dc313f8fdfee3f0a4572779ae13e27e40.
Re-fix bug #3319 with less side effects.
Removed an unnecessary workaround for matrix-to-vector copyTo.
Added a test for matrix-to-vector copy and convert.
Merge pull request #2140 from Daniil-Osokin:fix_saving_untrained_svm_model
Merge pull request #2159 from SpecLad:1xN
Merge remote-tracking branch 'origin/2.4' into merge-2.4

Conflicts:
	modules/ocl/src/cl_runtime/cl_runtime.cpp
	modules/ocl/src/cl_runtime/clamdblas_runtime.cpp
	modules/ocl/src/cl_runtime/clamdfft_runtime.cpp
	modules/ocl/src/cl_runtime/generator/template/clamdblas_runtime.cpp.in
	modules/ocl/src/cl_runtime/generator/template/clamdfft_runtime.cpp.in
Merge pull request #2176 from SpecLad:merge-2.4