The latest configure invocation was saved in config-host.mak and could
be extracted from that file to recreate the configuration.

Now it is saved in a new file config.status which can be directly executed
to recreate the configuration. The file name and the comments were copied
from GNU autoconf.

Makefile now uses config.status, but also includes transitional code
for the old mechanism.
Signed-off-by: NStefan Weil <sw@weilnetz.de>
Reviewed-by: NFam Zheng <famz@redhat.com>