We freed the string containing the final datadir path, but did not free
the path to the executable's directory that we get from
g_path_get_dirname(). Fix that.

Reported-by: Thomas Huth <thuth@redhat.com>
Signed-off-by: Alexander Bulekov <alxndr@bu.edu>
Message-Id: <20200717163523.1591-1-alxndr@bu.edu>
Signed-off-by: Thomas Huth <thuth@redhat.com>