Re: pgsql: Add support for OAUTHBEARER SASL mechanism

> Add support for OAUTHBEARER SASL mechanism

Debian still has this experimental port with a GNU userland and a
FreeBSD kernel called kfreebsd. I don't expect anyone to particularly
care about it, but it found an actual bug:

/build/reproducible-path/postgresql-18-18~~devel.20250331/build/../src/interfaces/libpq/fe-auth-oauth-curl.c: In function ‘register_socket’:
/build/reproducible-path/postgresql-18-18~~devel.20250331/build/../src/interfaces/libpq/fe-auth-oauth-curl.c:1317:20: error: ‘actx’ undeclared (first use in this function); did you mean ‘ctx’?
1317 | actx_error(actx, "libpq does not support multiplexer sockets on this platform");
| ^~~~

This should not be a compile-time error; actx is not defined outside
the #ifdef blocks there:

/*
* Adds and removes sockets from the multiplexer set, as directed by the
* libcurl multi handle.
*/
static int
register_socket(CURL *curl, curl_socket_t socket, int what, void *ctx,
void *socketp)
{
#ifdef HAVE_SYS_EPOLL_H
struct async_ctx *actx = ctx;
...
#endif
#ifdef HAVE_SYS_EVENT_H
struct async_ctx *actx = ctx;
...
#endif

actx_error(actx, "libpq does not support multiplexer sockets on this platform");
return -1;
}

https://buildd.debian.org/status/fetch.php?pkg=postgresql-18&arch=hurd-amd64&ver=18%7E%7Edevel.20250331-1&stamp=1743455288&raw=0

Christoph