GPL license on fy-list.h

[Enjection]

It seem's that it is forbidden to licesne your library under MIT license with code licensed under GPL2.0 in it.

[pantoniou]

Up to now people didn't object much (GPL2 is much less viral than GPL3).

Another reason is that using the Linux kernel's list implementation makes things easier to integrate in the kernel (when/if that time comes).

For commercial applications a pure MIT library has merits.

I will continue this discussion at the pull request...

[bkmgit]

Maybe it is helpful to indicate in the README that fy-list.h is GPL2 and and xxhash is BSD-2-Clause