It's not documented, and it does nothing unless CMake 2.0 compatibility
is enabled (and it isn't):

https://github.com/Kitware/CMake/blob/v2.6.0/Source/cmConfigureFileCommand.cxx

Added opencv_testing.sh.in file;
opencv_testing.sh installation guarded by OS check.

CV_CAP_PROP_SUPPORTED_PREVIEW_SIZES_STRING property is not supported
by all VideoCapture backends. Some backends can return 0.0 or -1.0.

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.

fill destination matrix with zeros if it was reallocated

Fixed bug #3489: The code assumed that two global variables would be constructed in a particular order, but global variable initialization order is compiler-dependent.

See 092f916d for explanation.

This reverts commit 4f9c081d.