I wish I could offer more help than I can... I don't have
access to an IRIX installation to fix the signal problems
or the linkage problems... I'm hoping someone on abiword-dev
(which I've added to this reply) will have recent news on this.
I suspect making AbiWord compile on IRIX will be #ifdef'ing
the popen and signal setup calls for builds under IRIX and
perhaps tweaking abi/src/config/platforms/irix.mk to include
any link flags it needs.
-- Shaw Terwilliger