scripts: unset CONFIG_SITE

Some distributions (eg. openSUSE 12.1) systematically export
the CONFIG_SITE environment variable to point to a custom
script setting misc paths for ./configure.

This can, and does, break when cross-compiling for architectures
that are not supported by this script.

The simple workaround is to unset this variable.
NB: buildroot has a similar fix:
http://git.buildroot.org/buildroot/commit/?id=12c9f7dd6dee9c6029b4f9a12d6aac1516911ab4

Reported-by: Trevor Woerner <twoerner@gmail.com>
Signed-off-by: "Yann E. MORIN" <yann.morin.1998@anciens.enib.fr>
(transplanted from 21f4f28e60ec0342133086c9a51e7f0e5b181fb8)

diff -durN binutils-2.20.1.orig/ld/ldmain.c binutils-2.20.1/ld/ldmain.c

--- binutils-2.20.1.orig/ld/ldmain.c	2010-08-17 19:32:17.000000000 +0200

+++ binutils-2.20.1/ld/ldmain.c	2010-08-17 19:32:18.000000000 +0200

@@ -264,6 +264,7 @@

   link_info.keep_memory = TRUE;

   link_info.new_dtags = TRUE;

   link_info.combreloc = TRUE;

+  link_info.relro = TRUE;

   link_info.strip_discarded = TRUE;

   link_info.emit_hash = TRUE;

 #ifndef __mips__