bad posix_fadvise support causes initdb to exit ungracefully

Due to unfortunate environmental conditions (don't ask) I've been
trying to get postgres 9.0 up and running on a fairly ancient linux --
redhat EL 3 which as kernel 2.4.21. initdb borks on the create
database step with the error message "child process exited with error
code 139". A bit of tracing revealed the exit was happening at the
pg_flush_data which basically wraps posix_fadvise. Disabling fadvise
support in pg_config_manual.h fixed the problem.

Things brings up a couple of questions:
*) Are linuxes this old out of support?
*) Should configure be testing for working posix_fadvise?

merlin