Cherry-pick from PG13: Go back to returning int from ereport auxiliary functions.

[reshke]

I was casually compiling Cloudberry with some postrgesql extensions and faced a compile issue:

/usr/local/cbdb/include/postgresql/server/utils/elog.h:215:13: error: conflicting declaration of C function ‘void errmsg_internal(const char*, ...)’
  215 | extern void errmsg_internal(const char *fmt,...) pg_attribute_printf(1, 2);
      |             ^~~~~~~~~~~~~~~

This is basically because contents of postgres/postgres@bda6ded is missing in cbdb. So, lets cherry-pick it

original commit msg follows:

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This reverts the parts of commit 17a28b0 that changed ereport's auxiliary functions from returning dummy integer values to returning void. It turns out that a minority of compilers complain (not entirely unreasonably) about constructs such as

(condition) ? errdetail(...) : 0

if errdetail() returns void rather than int. We could update those call sites to say "(void) 0" perhaps, but the expectation for this patch set was that ereport callers would not have to change anything. And this aspect of the patch set was already the most invasive and least compelling part of it, so let's just drop it.

Per buildfarm.

Discussion: https://postgr.es/m/CA+fd4k6N8EjNvZpM8nme+y+05mz-SM8Z_BgkixzkA34R+ej0Kw@mail.gmail.com

Fixes #ISSUE_Number

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