Codegen error handlers aren't emitting any errors

[svhawkins]

Ttile.

Some intentionally-error-triggering codegen tests are failing since error_status is not being updated (it stays at 0 ('clean')). Same goes for global_error_status. Stepping through some of these tests in GDB reveal that they are in fact going to the handlers, but error_status fails to recognize that.

Possibile culprit(s):

1. Not being updated in the error handler(s)
2. Not being 'passed along' all the way down and gets overwritten

Possible solution(s):

1. Have error_status be specific to each module/structure/compiler pass:

• Have an expr_error_status, decl_error_status, etc. for each of the passes
• Or typecheck_error_status, codegen_error_status, etc.

2. Pass it in as a pass-by-pointer parameter instead of returning it

This is a minor issue. This does not block overall code generation (if anything it's just a losing a sanity check or 2).