[R]: remove FlashGraph in Makevars of FlashR.
[R]: remove FlashGraph in Makevars of FlashR.

icoming/FlashX,icoming/FlashX,flashxio/FlashX,flashxio/FlashX,flashxio/FlashX,icoming/FlashX,flashxio/FlashX,icoming/FlashX,flashxio/FlashX,flashxio/FlashX,icoming/FlashX