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.

configure

@@ -27415,6 +27415,9 @@ ac_config_headers="$ac_config_headers src/include/pg_config.h"
 ac_config_headers="$ac_config_headers src/interfaces/ecpg/include/ecpg_config.h"
+# This comment is to lengthen the configure script to dodge this ksh93 bug:
+# https://mailman.research.att.com/pipermail/ast-developers/2010q4/000797.html
+
 cat >confcache <<\_ACEOF
 # This file is a shell script that caches the results of configure
 # tests run on this system so they can be shared between configure

configure.in

@@ -1878,6 +1878,9 @@ echo >src/include/stamp-h
 AC_CONFIG_HEADERS([src/interfaces/ecpg/include/ecpg_config.h],
                   [echo >src/interfaces/ecpg/include/stamp-h])
 
+# This comment is to lengthen the configure script to dodge this ksh93 bug:
+# https://mailman.research.att.com/pipermail/ast-developers/2010q4/000797.html
+
 AC_OUTPUT
 
 # Warn about unknown options