Badly designed error reporting code in controldata_utils.c

My attention was drawn to the log_error() stuff in controldata_utils.c by
the fact that buildfarm member pademelon spit up on it.  The reason for
that compile failure is that pademelon's dinosaur of a compiler doesn't
support __VA_ARGS__.  I do not feel a need to get into a discussion about
whether we should move our portability goalposts for the convenience of
this commit, because there are other reasons why this is a crummy solution
for error reporting:

* It uses elog() not ereport() for what seems a not-particularly-internal
error, which among other things means that an entirely inappropriate
errcode() will be reported.

* It relies on strerror(errno), not %m, which may not work reliably even
in elog() and certainly won't in ereport() (because of order-of-evaluation
uncertainties).

* Translatability of the error message in the frontend context seems
a bit dubious; generally we let translators work with the whole string
to be printed, not just part of it.

* It's randomly unlike every single other place we've addressed the
same problem.  Everywhere else in src/common does it like this:

#ifndef FRONTEND       ereport(ERROR,               (errcode(ERRCODE_PROGRAM_LIMIT_EXCEEDED),
errmsg("outof memory")));
 
#else       fprintf(stderr, _("out of memory\n"));       exit(EXIT_FAILURE);
#endif

and I think that's what this needs to do too, especially in view of the
fact that there are only two places that would have to be fixed anyway.
        regards, tom lane