The current configure option --enable-bluetooth is a bit misleading,
it doesn't really tell what it's actually for. Therefore renamed it,
so it's more clear that it's an sdremote backend using bluetooth.

Change-Id: Ia8b46ee001ea112b80521baa502dcab2bb7e83aa
Reviewed-on: https://gerrit.libreoffice.org/1086Reviewed-by: Rene Engelhard <rene.engelhard.re@googlemail.com>
Tested-by: Rene Engelhard <rene.engelhard.re@googlemail.com>