Add script to fix file names in upstream patches

Add script to fix file names in upstream patches

Added a simple sed script to do a search and replace on the Illumos
ZFS file names and replace them with the ZFS on Linux equivalent.

Example usage:

    # Replace Illumos paths with Linux paths
    $ ./scripts/zfs2zol-patch.sed arc.c.patch > arc.c.patch.linux

    # Ensure the script worked as expected
    $ diff arc.c.patch arc.c.patch.linux

    # Apply the patch using Linux paths
    $ patch -p1 < arc.c.patch.linux

Signed-off-by: Richard Yao <ryao@gentoo.org>
Signed-off-by: Prakash Surya <surya1@llnl.gov>
Signed-off-by: Brian Behlendorf <behlendorf1@llnl.gov>
Closes #1679