Make it possible for enqueue_map tests to catch more USE_HOST_PTR issues (#730)

* Make it possible for enqueue_map tests to catch more USE_HOST_PTR issues

Don't update the memory passed as host_ptr with the correct result
and compute the reference result using a separate allocation so that
implementations that use copies to manage the host_ptr and never update
as part of map/unmap commands the memory pointed to by host_ptr fail
the test.

Rename initialData to hostPtrData for clarity.

Fixes #700

Signed-off-by: Kévin Petit <kpet@free.fr>

* format fixes

* more format fixes?