Back out gcc workaround per re@ request. Details:

Back out gcc workaround per re@ request. Details:
"There seems to be some continuing discussion about how this is best fixed,
and we'd like to get Alexander (as our gcc guru) to opine on a final
solution before picking one.  In the mean time, could you back out the
original commit (sys.mk:1.89)?"

Approved by:	re (rwatson)