Kprobes: move kprobe examples to samples/

Kprobes: move kprobe examples to samples/

Move kprobes examples from Documentation/kprobes.txt to under samples/.
Patch originally by Randy Dunlap.

o Updated the patch to apply on 2.6.25-rc3
o Modified examples code to build on multiple architectures. Currently,
  the kprobe and jprobe examples code works for x86 and powerpc
o Cleaned up unneeded #includes
o Cleaned up Kconfig per Sam Ravnborg's suggestions to fix build break
  on archs that don't have kretprobes
o Implemented suggestions by Mathieu Desnoyers on CONFIG_KRETPROBES
o Included Andrew Morton's cleanup based on x86-git
o Modified kretprobe_example to act as a arch-agnostic module to
  determine routine execution times:
	Use 'modprobe kretprobe_example func=<func_name>' to determine
	execution time of func_name in nanoseconds.

Signed-off-by: Randy Dunlap <[email protected]>
Signed-off-by: Ananth N Mavinakayanahalli <[email protected]>
Acked-by: Mathieu Desnoyers <[email protected]>
Signed-off-by: Andrew Morton <[email protected]>
Signed-off-by: Linus Torvalds <[email protected]>