Install lib64stdc++ in install-chroot.sh.

build/install-chroot.sh

Index: build/install-chroot.sh
diff --git a/build/install-chroot.sh b/build/install-chroot.sh
index ae97d539d054eef5681c3df16bd5f4dc9a60dd30..d3b83878a1cd67267086705ae606ae1838acb980 100755
--- a/build/install-chroot.sh
+++ b/build/install-chroot.sh
@@ -659,7 +659,7 @@ if [ "${copy_64}" = "y" -o \
   readlinepkg=$(sudo "/usr/local/bin/${target%bit}" sh -c \
     'apt-cache search "lib64readline.\$" | sort | tail -n 1 | cut -d " " -f 1')
   sudo "/usr/local/bin/${target%bit}" apt-get -y install                       \
-    lib64expat1 lib64ncurses5 ${readlinepkg} lib64z1
+    lib64expat1 lib64ncurses5 ${readlinepkg} lib64z1 libstdc++6:amd64

[Junichi Uekawa, 2014/10/17 07:29:18]

a bit worrysome that lib64 version and :amd64 version coexists.

I think you should keep them consistent and use lib64stdc++6 here.
One day we should probably migrate all to <package>:amd64.

[Yoshisato Yanagisawa, 2014/10/17 07:40:37]

Done.

   dep=
   for i in binutils gdb; do
     [ -d /usr/share/doc/"$i" ] || dep="$dep $i"