[PATCH] Always do locking when accessing streams (bug 15142, bug 14697)

[Szabolcs Nagy]

On 25/11/2019 14:20, Andreas Schwab wrote:
> Now that abort no longer calls fflush there is no reason to avoid locking
> the stdio streams anywhere.

the patch looks ok to me.

note that it may expose an issue mentioned in

https://sourceware.org/bugzilla/show_bug.cgi?id=24963

concurrent fflush(0) and freopen(fp) may deadlock
as they choose different lock ordering.