IVGCVSW-4487 Remove boot/dll.hpp from dynamic backends test.

IVGCVSW-4487 Remove boot/dll.hpp from dynamic backends test.

* Replace the call to boost::dll::program_location() with a cmake
  variable set at runtime. PROJECT_BINARY_DIR appears to fit the bill.
* Fall back to a boost custom CLI to allow it to be user specified.
* Add a FAQ entry describing potential problems.
* Adding flexibility to GetSharedObjectsTestImpl to cope with
  sym links in file systems.

Signed-off-by: Colm Donelan <Colm.Donelan@arm.com>
Change-Id: Iccf3f1b0f2911101e1f61bffd73cefba271bbfe2