Update FreeBSD elf_common.h.

Looks like I'd been bad here, and added new stuff to this file rather
than <elf.h> directly. I've also done nothing to upstream any of this.
This patch at least addresses the former problem, moving our stuff out
into <elf.h>.

Rather than *delete* anything that conflicts with Linux in elf_common.h,
I've disable it with // or #if, and marked those as Android changes to
make it less likely that the next update accidentally drops them (which
isn't super likely, since most of them should actually cause build
failures when they conflict with uapi).

Test: treehugger
Change-Id: Id0deccc7305c60b0f708b55e2eed0dedc0bca41d
diff --git a/libc/NOTICE b/libc/NOTICE
index 91cd335..dfd93ff 100644
--- a/libc/NOTICE
+++ b/libc/NOTICE
@@ -4640,7 +4640,9 @@
 
 SPDX-License-Identifier: BSD-2-Clause
 
-Copyright (c)1999 Citrus Project,
+Copyright (c) 2017, 2018 Dell EMC
+Copyright (c) 2000, 2001, 2008, 2011, David E. O'Brien
+Copyright (c) 1998 John D. Polstra.
 All rights reserved.
 
 Redistribution and use in source and binary forms, with or without
@@ -4666,11 +4668,9 @@
 
 -------------------------------------------------------------------
 
-SPDX-License-Identifier: BSD-2-Clause-FreeBSD
+SPDX-License-Identifier: BSD-2-Clause
 
-Copyright (c) 2017, 2018 Dell EMC
-Copyright (c) 2000, 2001, 2008, 2011, David E. O'Brien
-Copyright (c) 1998 John D. Polstra.
+Copyright (c)1999 Citrus Project,
 All rights reserved.
 
 Redistribution and use in source and binary forms, with or without