Ranger: Mark a few classes as final

Ranger: Mark a few classes as final

I noticed there was a warning from clang about int_range's
dtor being marked as final saying the class cannot be inherited from.
So let's mark the few ranger classes as final for those which we know
will be final.

Bootstrapped and tested on x86_64-linux-gnu.

gcc/ChangeLog:

	* value-range.h (class int_range): Mark as final.
	(class prange): Likewise.
	(class frange): Likewise.

Signed-off-by: Andrew Pinski <quic_apinski@quicinc.com>