elfutils: Fix build with uclibc/musl

Remove mempcpy patch its already in uclibc now
refresh libargp patch to match latest elfutils

Add ALLOW_EMPTY for musl

core-image-cmdline-full asks for elfutils package to be added to package
it has all eu-* tools but we dont build them on musl. nevertheless lets
satisfy the dependency so image can build for musl

Build libdw,libasm,libebl along with libelf

enhance the musl portability patch to compile every other library
except the eu-* tools

Fix build on aarch64/musl issues

Header inclusion ends up with duplicate definitions of iovec struct
since uclibc defines the same in usersapce, we have been depending upong
including the kernel header on aarch64, using sys/uio.h is the right
approach

Fix x86 build warning seen on musl

Signed-off-by: Khem Raj <raj.khem@gmail.com>