DRAFT: ignore FS_IOC_FIEMAP failure with ENOTSUPP

[ofaaland]

Lustre can return ENOTSUPP (524) in response to an FS_IOC_FIEMAP ioctl() call, for a file striped a certain way.

The file can still be copied, fiemap just can't tell us where the holes are.

A brief survey using google searches suggests ENOTSUPP (524) was historically intended for use internal to the kernel or drivers, but has occasionally been returned to users by different software, in ways that have meaning similar to ENOTSUP.

Ignore the error as with ENOTSUP (95) so the file is copied without the use of fiemap.

Fixes #644