objcopy: Always use ELF Tool Chain objcopy for EFI builds

[emaste]

Summary

It is required as part of our EFI object build process, as llvm-objcopy
does not support efi-app-x86_64 and similar ouptut (for more detail
see https://github.com/llvm/llvm-project/issues/108609).

PR:             280771

[emaste]

We could always install it as elftc-objcopy and add LINKS+= ${BINDIR}/${PROG} ${BINDIR}/objcopy in the MK_LLVM_OBJCOPY=no case and set EFI_OBJCOPY?= elftc-objcopy always; reviewers let me know if you think that's preferable/simpler.

Will also need an addition to ObsoleteFiles.inc/OptionalObsoleteFiles.inc.

[mpysw_vip.163.com]

stand/efi/Makefile.inc

30

Let's use its original name, elfcopy

[emaste]

use elfcopy name

[emaste]

add OptionalObsoleteFiles.inc

[emaste]

tools/build/mk/OptionalObsoleteFiles.inc

8128

these shouldn't be conditional on LLVM_BINUTILS, will remove locally

[andrew]

Will you need to remove elfcopy from ObsoleteFiles.inc? (20161003: MK_ELFCOPY_AS_OBJCOPY option retired)

[emaste]

Remove ObsoleteFiles.inc entry

[emaste]

diff against correct version

[andrew]

We could probably switch to llvm-objcopy for loader.efi on non-x86, but that can be a followup change