The local symbol relocations are a bit different from
llvm-mc, which are section-relative. E.g., instead "bytes",
it will be ".data + offsetof(bytes, .data)". So the
contents of the text/data/rodata sections can also differ
since the offsets written in place are different.

Still need to fill the symbol table with undefined
symbols (e.g., memset, and szrt lib functions) before
trying to link.

BUG=none
R=kschimpf@google.com, stichnot@chromium.org

Review URL: https://codereview.chromium.org/874353006