musl: Update to 1.2.2

Backport musl 1.2.2 from poky master.
This is in sync with commit 4da1e8091ea0a57209519f0a4755d06aa108f439

musl 1.2.2 brings, among other things, a number of important bugfixes and
a much better malloc implementation.

Signed-off-by: Bernhard Rosenkränzer <bernhard.rosenkraenzer.ext@huawei.com>