script: optionally compile with libutempter to update utmp

script: optionally compile with libutempter to update utmp

Use --with-utempter to enable utempter support. The libutempter calls
/usr/libexec/utempter/utempter suid helper to update utmp and wtmp
files.

Old version:
	$ script
	Script started, file is typescript

	$ who i am

	$ exit
	Script done, file is typescript

New version:
	$ script
	Script started, file is typescript

	$ who i am
	kzak     pts/6        2010-04-29 12:30

	$ exit
	Script done, file is typescript

Addresses: http://bugzilla.redhat.com/show_bug.cgi?id=477753
Signed-off-by: Karel Zak <kzak@redhat.com>