- Rebase on 2.20.51.0.7 tarball.
    - Delete redundant patches: binutils-2.20.51.0.2-add-needed.patch,
        binutils-2.20.51.0.2-do-not-set-ifunc.patch,
        binutils-2.20.51.0.2-enable-gold.patch,
        binutils-2.20.51.0.2-gas-expr.patch,
        binutils-2.20.51.0.2-ifunc-ld-s.patch, binutils-2.20.51.0.2-lwp.patch,
        binutils-2.20.51.0.2-ppc-hidden-plt-relocs.patch,
        binutils-2.20.51.0.2-x86-hash-table.patch,
    - Do not allow unique symbols to be bound locally. (PR ld/11434)
    - Add support for DWARF4 debug information.