binutils/readelf: handle NT_AMDGPU_METADATA note name

binutils/readelf: handle NT_AMDGPU_METADATA note name

Handle the NT_AMDGPU_METADATA note, which is described here:

  https://llvm.org/docs/AMDGPUUsage.html#code-object-v3-note-records

As of this patch, just print out the name, not the contents, which is in
the msgpack format.

binutils/ChangeLog:

	* readelf.c (get_amdgpu_elf_note_type): New.
	(process_note): Handle "AMDGPU" notes.

include/ChangeLog:

	* elf/amdgcn.h (NT_AMDGPU_METADATA): New.

Change-Id: Id2dba2e2aeaa55ef7464fb35aee9c7d5f96ddb23