objtool: Resync objtool's instruction decoder source code copy with the kernel's latest version

This fixes the following warning:

  warning: objtool: x86 instruction decoder differs from kernel
Reported-by: Stephen Rothwell <sfr@canb.auug.org.au>
Signed-off-by: Josh Poimboeuf <jpoimboe@redhat.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Link: http://lkml.kernel.org/r/013315a808ccf5580abc293808827c8e2b5e1354.1509719152.git.jpoimboe@redhat.comSigned-off-by: Ingo Molnar <mingo@kernel.org>

tools/objtool/arch/x86/insn/gen-insn-attr-x86.awk

 #!/bin/awk -f
+# SPDX-License-Identifier: GPL-2.0
 # gen-insn-attr-x86.awk: Instruction attribute table generator
 # Written by Masami Hiramatsu <mhiramat@redhat.com>
 #