Incorrect bitfield aliasing with Tree SSA

[Richard Kenner]

> Type of the expression passed to get_alias_set.  And without the
> component_uses_parent_alias_set loop.

So you mean the type of the *field*?  That can't work.  That type can't
be used for *anything*!

Otherwise, if you have

	struct foo {int a: 32; int b: 32; };
	struct bar {int c: 32; int d: 32; };

you have the fields A and C conflicting, which is wrong.

The "T" has to be the *record type*, so that when you share alias sets,
it's the same for every type in the same record, not every occurence of
some random type in different records.