diff -up emacs-23.1/configure.in.cpp emacs-23.1/configure.in

--- emacs-23.1/configure.in.cpp	2009-11-30 13:24:53.000000000 +0100

+++ emacs-23.1/configure.in	2009-11-30 13:25:45.000000000 +0100

@@ -2983,7 +2983,7 @@ echo creating lib-src/Makefile

   sed -e '1,/start of cpp stuff/d'\

       -e 's,/\*\*/#\(.*\)$,/* \1 */,' \

       < Makefile.c > junk.c

-  $CPP $cpp_undefs -I. -I$srcdir/src $CPPFLAGS junk.c | \

+  $CPP -P $cpp_undefs -I. -I$srcdir/src $CPPFLAGS junk.c | \

       sed -e 's/^ /	/' -e '/^#/d' -e '/^[ 	?]*$/d' > junk2.c

   cat junk1.c junk2.c > Makefile.new

   rm -f junk.c junk1.c junk2.c

@@ -2999,7 +2999,7 @@ echo creating src/Makefile

   sed -e '1,/start of cpp stuff/d'\

       -e 's,/\*\*/#\(.*\)$,/* \1 */,' \

       < Makefile.c > junk.c

-  $CPP $cpp_undefs -I. -I$srcdir/src $CPPFLAGS junk.c | \

+  $CPP -P $cpp_undefs -I. -I$srcdir/src $CPPFLAGS junk.c | \

       sed -e 's/^ /	/' -e '/^#/d' -e '/^[ 	?]*$/d' > junk2.c

   cat junk1.c junk2.c > Makefile.new

   rm -f junk.c junk1.c junk2.c