tools lib lk: Fix for cross build

tools lib lk: Fix for cross build

Currently, lib lk doesn't use CROSS_COMPILE environment variable, so
cross build always fails.

This is a quick fix for this problem.

Signed-off-by: Joonsoo Kim <[email protected]>
Cc: Ingo Molnar <[email protected]>
Cc: Namhyung Kim <[email protected]>
Cc: Paul Mackerras <[email protected]>
Cc: Peter Zijlstra <[email protected]>
Link: http://lkml.kernel.org/r/[email protected]
Signed-off-by: Arnaldo Carvalho de Melo <[email protected]>