binfmt_elf.c: use get_random_int() to fix entropy depleting

https://patchwork.kernel.org/patch/1745611/

Signed-off-by: Keff <funnykeff91@gmail.com>
page-writeback: dirty page tweaks

https://github.com/franciscofranco/Tuna_JB_pre1/commit/405dbcc9eb0b109bff906b3bd25b7f8ce9e2acac

Signed-off-by: Keff <funnykeff91@gmail.com>
Revert lib/memcopy and lib/string

sorry for that..