We generate DWARF types for channels containing various specific types.
For a make(chan bool), for example, we generate hchan, sudog, and waitq DWARF types so we could make these types specific in the output.

The sudog contains a field called elem which points to the element to be sent or received. It has a type of unsafe.Pointer. To make a specific sudog type, we overwrite the elem field's type with the type of the element. That's wrong, we should overwrite with the pointer to-the-element type.

The DWARF is most plainly wrong when the element type isn't the size of a pointer. Then not only is the elem field wrong, but all the subsequent fields in the sudog are at the wrong offsets. (That's how I noticed this.)

I have a fix, just thinking about a test.
Looks like it has been broken since at least go1.7, so not a regression. Marking 1.10.

@matloob @heschik @derekparker