Update those break statements inside case clauses that are intended to reach an
enclosing for loop, so that they correctly exit the loop.
The candidate files for this change were located using:
% staticcheck -checks SA4011 ./... | cut -d: -f-2
This change is intended to preserve the intended semantics of the code, but
since the code as-written did not have its intended effect, some behaviour may
change. Specifically: Some loops may have run longer than they were supposed
to, prior to this change.
In one case I was not able to clearly determine the intended outcome. That case
has been commented but otherwise left as-written.
Fixes#6780.
