extra: filter PARAM_VALUEs with both extra and real_absolute
The problem is that we sometimes record a PARAM_VALUE as s32min-10 when
it should be 0-10. The example code looks something like this:
int a = unknown_u8;
if (a > 10)
return;
frob(a);
Smatch_extra looks at the initial assignment and says it doesn't tell us
anything. Real absolute looks at it and says a is 0-255. Smatch extra
see the comparison and says that is less than 11 so s32min-10. Now in
the new code, when we call frob() we combine those to say that the param
value is 0-10.
Signed-off-by: Dan Carpenter <dan.carpenter@oracle.com>