unchecked out of memory in postmaster.c

Hi,

Some time ago I noticed that in postmaster.c there's a corner case which
probably causes postmaster to exit in out-of-memory condition.  See
BackendStartup, near the bottom, there's a call to DLNewElem().  The
problem is that this function calls palloc() and thus can elog(ERROR) on
OOM, but postmaster has no way to defend itself from this and would die.

I haven't ever seen postmaster die from this, but I don't think it's a
good idea to let it be like this, given the strict promises we make
about its reliability.  Probably a simple PG_TRY block around the
DLNewElem call suffices ...?

-- 
Alvaro Herrera                                http://www.CommandPrompt.com/
The PostgreSQL Company - Command Prompt, Inc.