CONSTRAINT__LIMIT

[DJ Delorie]

> Ian, thanks for reporting this.  I'll investigate this more.  It
> affects only ports using priority allocation (I know only one which
> is m32c).  DJ just recently reported a reload failure problem on
> m32c.  Probably that is because of this wrong code.

In checking through this code, I see that it depends on having
define_constraint's in the *.md file.  m32c has none, so this code is
not triggered.  Has any port ever used this code?  Would the lack of
define_constraints be causing problems for the m32c backend?