[PATCH] x86_64: Align data segment to PAGE_SIZE boundary

o Explicitly align data segment to PAGE_SIZE boundary otherwise depending on
  config options and tool chain it might be placed on a non PAGE_SIZE aligned
  boundary and vmlinux loaders like kexec fail when they encounter a
  PT_LOAD type segment which is not aligned to PAGE_SIZE boundary.

Signed-off-by: Vivek Goyal <vgoyal@in.ibm.com>
Signed-off-by: Andi Kleen <ak@suse.de>