Fix incorrect help strings for configure options

The help strings for the timeout and delay configure options incorrectly
says that the default value is the number of seconds used if the option
is set. The default is however not to use any of them.

Signed-off-by: Marcus Karlsson <mk@acc.umu.se>
Prefix all with variables with `with_'

The variables used to hold the with-configure options are not named
consistently. Prefix all of them with the prefix `with'.

Signed-off-by: Marcus Karlsson <mk@acc.umu.se>
Show build summary at end of configure

It's useful to get a summary of the features and settings that will be
used during the build. Show this at the end of the configure script.

Signed-off-by: Marcus Karlsson <mk@acc.umu.se>