BUG #2445: incompatibility: realloc <> repalloc

The following bug has been logged online:

Bug reference:      2445
Logged by:
Email address:      friedrich_sperling@web.de
PostgreSQL version: 8.1.3
Operating system:   Debien GNU/Linux Etch
Description:        incompatibility: realloc <> repalloc
Details:

it seems that there is a little difference in the handeling of standard
library's realloc and the postgresql repalloc functions, which might be
inconvenient.
if the realloc funtion receives a NULL pointer as first argument, it works
just like the malloc function,
whereas the repalloc function crashes the server.