Install test data on Windows platform too

if `OPENCV_TEST_DATA_PATH` CMake option was set and `INSTALL_TESTS` is `TRUE`.
CPack uses permissions from FS without changes. If user umask is configured not correctly we always be in trouble. The problem can be solved by build automation like BuildBot easer, especially with recursive installation. I propose to remove comment, but we need to mention the problem in some document about packaging.
:+1: