changes to copy_file broke MakeCp's files_to_copy for symlinks being copied to non-existing directory

[akesandgren]

See for instance jbigkit, before that commit it works, after that commit it fails with:

Failed to copy file /scratch/eb-buildpath/jbigkit/2.1/GCCcore-10.3.0/jbigkit-2.1/libjbig/libjbig85.so to /hpc2n/eb/software/jbigkit/2.1-GCCcore-10.3.0/lib: [Errno 22] Invalid argument: '/hpc2n/eb/software/jbigkit/2.1-GCCcore-10.3.0/lib' (at easybuild/ake/eb-develop/easybuild-framework/easybuild/tools/filetools.py:2301 in copy_file

when copying the 2nd file in the list

files_to_copy = [
    (['libjbig/libjbig%s.%s' % (x, y) for x in ['85', ''] for y in ['a', SHLIB_EXT, SHLIB_EXT + '.0']], 'lib'),

[boegel]

Duplicate issue, see #3854, fixed by #3855