Cleanup: add Elf namespace with typedefs for ElfW types
Cleanup: add Elf namespace with typedefs for ElfW types

This looks much nicer in the C++ code below, and plays better with
clang-format as well.

muojp/heaptrack,muojp/heaptrack,muojp/heaptrack,muojp/heaptrack,muojp/heaptrack