[LINUX] Move .bss declaration after .data.* in x86_64 linker script.

[LINUX] Move .bss declaration after .data.* in x86_64 linker script.

Older binutils (prior to 2.16) have a problem with the linker script resulting
from the change introducing explicit segment maps. Namely does the
respective linker not properly handle @nobits sections (i.e. .bss) sitting
between @progbits ones (i.e. .data.*). The .bss section must therefore
be moved past all initialized sections (as is already the case on i386).
Replacement patch attached.

From: Jan Beulich <jbeulich@novell.com>
Signed-off-by: Ian Campbell <ian.campbell@xensource.com>