libfrog: add quotactl_fd support to xfsquotactl

Add support for the quotactl_fd syscall to the xfsquotactl call in
libfrog.  I rearranged the function arguments so that the fs connection
point (either an open fd or the fs source) come first.

Signed-off-by: "Darrick J. Wong" <djwong@kernel.org>
Reviewed-by: Christoph Hellwig <hch@lst.de>