exit() calls in libraries

Debian's package policy and quality check tool lintian reports the
following (among other things) on the postgresql-9.1 (and earlier)
packages:

X: libpq5: shlib-calls-exit usr/lib/libpq.so.5.4
X: libecpg6: shlib-calls-exit usr/lib/libecpg.so.6.3

which is explained as

I: shlib-calls-exit
N:
N: The listed shared library calls the C library exit() or _exit()
N: functions.
N:
N: In the case of an error, the library should instead return an
N: appropriate error code to the calling program which can then determine
N: how to handle the error, including performing any required clean-up.
[snip]

The report on libecpg is actually a false positive, because the exit()
call comes from get_progname() in path.c, which is not called from
functions in libecpg.

The cases in libpq are

* various places in fe-print.c calling exit(1) when malloc fails,
presumably having run out of memory, and
* in libpq-int.h the macro PGTHREAD_ERROR, which is called in
several places in fe-connect.c and fe-secure.c.

Are these appropriate behaviors? The fe-print.c stuff probably isn't
used much anymore. But the threading stuff is, and it encroaches on the
exit status space of the libpq-using program. And does it even make
sense to call exit() if the thread locking is busted? Maybe abort()
would work better?