scripts/gdb: If not building expat for gdb, disable

--with-expat=yes is unconditionally passed to the gdb configure
stage, instead of respecting the ${do_expat} decision.

Disable if not needed. Prevents error building canadian cross;

configure: error: expat is missing or unusable

Where configure stage fails to find expat on the host compiler.

Signed-off-by: "David Holsgrove" <david.holsgrove@xilinx.com>
Signed-off-by: Bryan Hundven <bryanhundven@gmail.com>
Message-Id: <4c4410a2a8aab24a29c5.1349244128@localhost.localdomain>
PatchWork-Id: 188711

diff -ru gdb-6.8.orig/bfd/sysdep.h gdb-6.8/bfd/sysdep.h

--- gdb-6.8.orig/bfd/sysdep.h	2007-07-03 16:26:42.000000000 +0200

+++ gdb-6.8/bfd/sysdep.h	2011-08-21 13:33:47.000000000 +0200

@@ -131,7 +131,7 @@

 extern PTR realloc ();

 #endif

-#if !HAVE_DECL_STPCPY

+#if !HAVE_DECL_STPCPY && !defined(stpcpy)

 extern char *stpcpy (char *__dest, const char *__src);

 #endif