parse_call_math: work around for loops

parse_call_math: work around for loops

The problem here starts with the fact that Smatch handles loops in a hacky
way.  Say we have a loop:

	for (n = 0; n < some_variable; n++) {
		if (frob())
			return n;
	}

Because of how Smatch handles loops it's implied that "n" is "0-s32max - 1"
but "n" hasn't been modified since we set "n = 0" because we only parse the
loop one time.  So when we're trying to tie "n" to a parameter we see that
actually "n" here always comes from the "n = 0" assignment.

So in terms of "math" then "n" is zero.  So the return value is
"0-2147483646[0]" where 0-2147483646 comes from smatch_extra.c and [0]
comes from parameter math.

But really we don't want to be returning literals as param math ever.  We
only want it in terms of parameters.  So it's fair enough to just add this
hack around and avoid fixing loops for now...

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