Sema: implement for_len

This also makes another breaking change to for loops: in order to
capture a pointer of an element, one must take the address of array
values. This simplifies a lot of things, and makes more sense than how
it was before semantically.

It is still legal to use a for loop on an array value if the
corresponding element capture is byval instead of byref.
321ccbdc52Andrew Kelley committed on 2/19/2023, 2:17:21 AMparent5029e53
4 files changedLine totals unavailable