COMP: Remove now optional LINK_DIRECTORIES param passed to SEMMacroBuildCLI

Within a same CMake project, a CMake target embeds information like
the link directory and it is not required to explicitly set the link
directories.

From the CMake documentation [1], "this command is rarely necessary.
Library locations returned by find_package() and find_library() are
absolute paths. Pass these absolute library file paths directly to
the target_link_libraries() command. CMake will ensure the linker
finds them."

The same apply for dependening project like SlicerExecutionModel.
Indeed, since SlicerExecutionModel commit fdb7e28b, targets are exported
and it is not required to explicitly specify the link directories to link
against ModuleDescriptionParser library.

Same explanation apply for vtkTeem and MRML Libraries. The associated
targets are exported since Slicer r16490 and the library are already CMake
targets.

Also remove reference to an unset variable "MRML_LIB_DIR" originally
introduced by r3886 where it was used without being set.

[1] http://www.cmake.org/cmake/help/v2.8.10/cmake.html#command:link_directories

git-svn-id: http://svn.slicer.org/Slicer4/trunk@21732 3bd1e089-480b-0410-8dfb-8563597acbee