- WITH_MKL option is enabled
- user doesn't specify MKLROOT/MKL_ROOT_DIR variables

Current version of search for MLKROOT environment variable is wrong and should be corrected to (DEFINED ENV{MKLROOT})

CMake should not fail.

* moved BLAS/LAPACK detection scripts from opencv_contrib/dnn to the main repository.

* trying to fix the bug with undefined symbols sgesdd_ and dgesdd_

* removed extra whitespaces; disabled LAPACK on IOS