Dodge an ancient ksh bug that breaks configure on some platforms.

Dodge an ancient ksh bug that breaks configure on some platforms.

8.4.10's configure script suddenly started failing on platforms that use
older versions of ksh as /bin/sh.  It turns out to be a ksh bug that's
triggered by here-document delimiters falling across bufferload boundaries:
https://mailman.research.att.com/pipermail/ast-developers/2010q4/000797.html

Hopefully this will get fixed before we trip over it again, but to make
8.4.10 releasable, add a comment to move the boundaries to dodge the bug.
Per buildfarm members koi and warthog, plus a report from Bjorn Munch of
the identical failure on Solaris 10.