klibc: add MIT License

* After a talk with Beth Flanagan licensing is now clear:
* "LICENSE = "BSD-3-Clause & GPL-2.0 & MIT" (If it's --without-zlib).
* If not then it's: LICENSE = "BSD-3-Clause & GPL-2.0 & MIT & Zlib"
* bump INC_PR

Signed-off-by: Andrea Adami <andrea.adami@gmail.com>
Signed-off-by: Koen Kooi <koen@dominion.thruhere.net>