glest is using jam instead of make.
because of this (probably) MAKEOPTS is not used.
from what I saw,
make and jam have 'at least' -j in common.
As I use distcc, this is very usefull. (this will be true even without distcc
as gentoo guide advise to have -j[N] even on single proc pc)
I tried replacing in the ebuild :
jam || die "jam failed"
by
JAMOPTS=`echo ${MAKEOPTS} |sed -e "s/.*\(-j ?[0-9]*\).*/\1/"`
jam ${JAMOPTS} || die "jam failed"
it worked very well and save me time.
some other MAKEOPTS (I only use this one) might be usefull, but to be sure, the
above code will filter and only keep the one I know works.