[Bug other/58312] libssp configure check for "usable vsnprintf" is broken on cross-compilers.

[brooks at gcc dot gnu.org]

http://gcc.gnu.org/bugzilla/show_bug.cgi?id=58312

--- Comment #4 from Brooks Moses <brooks at gcc dot gnu.org> ---
It turns out that we do need these symbols in libssp despite having a nice
plain x86-Linux environment.  We've got some precompiled blobs from
who-knows-where that want the "LIBSSP_1.0" version of the __vsnprintf_chk
symbol -- and, although our glibc exports __vsnprintf_chk, it of course exports
it with a "GLIBC_2.3.4" version.  Failure ensues.

So, for consistency for things that either explicitly declare -lssp or
otherwise end up with the LIBSSP symbol versions, I think it's nonetheless
useful to fix the libssp configure file for cross-compilation.

Thus, patch posted:
http://gcc.gnu.org/ml/gcc-patches/2013-09/msg00174.html