Don't clone all the states for every case statement.

Don't clone all the states for every case statement.

Smatch was running out of memory a lot because it did a
clone_slist_and_states() for every case statement.  With this change we
only clone the states right before we do a merge.

This change does make validation/sm_switch.c fail.

The problem with that switch is that we want to say if, "if x is not 1
and not 2 then we can eliminate these paths."  But we actually check
it separately, "if x is not 1 we eliminate this path.  If x is not 2 we
eliminate this other path", but we don't check the compound condition.

Switch statement are a bit different from if statements.  If we did an
if (x == 3)
        c->a = 1;
the test would actually pass.

I will fix this asap obviously.

Signed-off-by: Dan Carpenter <error27@gmail.com>