math: count some more things as implied

math: count some more things as implied

There are several levels of certainty represented in smatch_math.c.

known            - values
implied          - variables with one value
hard max         - definite max
fuzzy max        - the context seem to imply we can reach this
implied min/max  - <sort of ambiguous>
absolute min/max - fall back to the type information if no other max can
                   be determined

I guess that maximums are used to tell buffer overflows and integer
overflows.  So we need a different degree of certainty for each.

I introduce absolute max first, but that didn't work so I introduced hard
max.  Now I'm trying to put more and more of the stuff that was under
absolute max into the implied max.

Signed-off-by: Dan Carpenter <dan.carpenter@oracle.com>