[PATCH] kdump: sysrq trigger mechanism for kexec based crashdumps

Add a sysrq-trigger mechanism for kexec based crashdumps.  Alt-Sysrq-c
triggers a kexec based crashdump.

Signed-off-by: Hariprasad Nellitheertha <hari@in.ibm.com>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>