Re-introduce ERR_HOLD, which means that an error is treated like a
warning except for the last pass, but unlike ERR_PASS2 the error
message *will* be issued if another error happens on the same pass, just
like warnings.
This will be used to improve error messages on instruction mismatch.
Signed-off-by: H. Peter Anvin (Intel) <hpa@zytor.com>
1b939ecf3d