[PATCH] Don't puke on crfs.ko build if sparse isn't installed

[Zach Brown]

> +AC_CHECK_PROG(SPARSE, sparse, C=1)

Nicely done.  I committed a slight variant where we call the variable
KBUILD_SPARSE_ARGS.

  http://oss.oracle.com/mercurial/zab/crfs/rev/fd704af93615

- z