recent libm build breakage

[Robert Elz <kre%munnari.OZ.AU@localhost>]

I have made some hacks which seem to have the amd64 build working again.
I an looking at i386 now, and will then try evbarm builds.

But there's no way I can build all 73 of the ports - so if you're a
builder of HEAD on the less common ports, now would be a good time to
try.

I have a kind of feeling for what is likely to be needed to fix the
issues that have been occurring after all the new long double functions
were added, so feel free to just send me the error report (not the whole
build log please, just from a little before the first real build error)
and I will see if I can send you back a patch to try.

kre