Re: Avoiding concurrent calls to bindtextdomain()

I wrote:
> 0001 also gets rid of the possibility that pthread_mutex_init/
> pthread_mutex_lock could fail due to malloc failure. This seems
> important since default_threadlock() assumes that pthread_mutex_lock
> cannot fail in practice. I observe that ecpglib also assumes that,
> although it's using CreateMutex() which has documented failure
> conditions. So I wonder if we ought to copy this implementation
> back into ecpglib; but I've not done that here.

The cfbot seemed happy with v1, so here's a v2 that does copy that
code back into ecpglib. (I kind of wonder why this code exists in
libpq + ecpglib at all, rather than in src/port/; but that seems
like a refactoring exercise for another day.)

I double-checked that all the pthread_mutex_t variables in libpq
and ecpglib are static, so the change in that struct should not
pose an ABI hazard for back-patching.

Barring objections, I plan to push this pretty soon.

regards, tom lane