Revert "lib: memcopy: use glibc version"

This reverts commit 9dc8153359bd2ce9f793553317b4bd100f9421ca.
Revert "lib: string: use glibc version"

This reverts commit 65df6be72b846e9d18b26f76d33e938ce6884d03.
fixing build errors
Revert "Fixed XZ compression"

This reverts commit 03f1020ba26a2ccbaeb75069af5d0bd5e7219d1a.