bug#15690: meyering grep-2.14.51-7a35 fails on Ubuntu 13.10 x86-64

[Paul Eggert]

>   http://meyering.net/grep/grep-2.14.51-7a35.tar.xz

That snapshot fails "make check" on Ubuntu 13.10 x86-64.
However, when I generate a tarball from the same git source,
"make check" works for me.

I think I tracked this down to a discrepancy in the tools used
to build this snapshot.  But it's getting late so I hope someone
else can check this.

The snapshot fails because the three tests multibyte-white-space,
pcre-utf8, surrogate-pair all fail.  And they fail because
"printf '\x40'" prints "\x40" rather than "@".
And this happens because the tests are run with
/bin/sh, not /bin/bash; on Ubuntu /bin/sh is Dash
and Dash mishandles printf with '\x...'.  And this
happens because './configure' decides to make SHELL
/bin/sh rather than /bin/bash.  And I think *this*
happens because 'configure' was built with Autoconf
2.69.112-f181 rather than Autoconf 2.69 (this is
the Autoconf 2.69 shipped with Fedora 19).  The
respective 'configure' scripts are pretty hairy,
though, and I can't easily see why the meyering.net
snapshot went awry.