Use the smarter filedescriptor closing in bpipe.

Instead of closing the filedescriptors ourself (and a maximum
of 29 (32 - 3)) use fcntl(F_CLOSEM) or closefrom() library call
to perform what we really want e.g. close all unneeded filedescriptors
of the forked process.
Start to create defaultconfigs

We want to create default configurations for certain use cases. This
is the first try to create a good default config for disk-only backup.

Signed-off-by: Marco van Wieringen <marco.van.wieringen@bareos.com>
Rebuild configure.
Remove DVD example.

As DVD support is removed it doesn't make sense to have an example for
a DVD file device.