markup_oops.pl: add options to improve cross-sompilation environments

The markup_oops.pl have 3 troubles to support cross-compiler environment:
1.  It use objdump directly.
2.  It use modinfo to get the message of module.
3.  It use hex function that cannot support 64-bit number in 32-bit arch.

This patch add 3 options to markup_oops.pl:
1. -c CROSS_COMPILE	Specify the prefix used for toolchain.
2. -m MODULE_DIRNAME	Specify the module directory name.
3. Change hex function to Math::BigInt->from_hex.

After this patch, parse the x8664 oops in x86, we can:
cat amd64m | perl ~/kernel/tmp/m.pl -c /home/teawater/kernel/bin/x8664- -m ./e.ko vmlinux

Thanks,
Hui

Signed-off-by: Hui Zhu <teawater@gmail.com>
Cc: Andrew Morton <akpm@linux-foundation.org>
Cc: Arjan van de Ven <arjan@linux.intel.com>
Cc: Sam Ravnborg <sam@ravnborg.org>
Cc: ozan@pardus.org.tr
Cc: Matthew Wilcox <willy@linux.intel.com>
Acked-by: WANG Cong <xiyou.wangcong@gmail.com>
Signed-off-by: Michal Marek <mmarek@suse.cz>