tools subcmd: Add missing NORETURN define for parse-options.h

parse-options.h uses the NORETURN macro without defining it.  perf
doesn't see a build error because it defines the macro in util.h before
including parse-options.h.  But any other tool including it will see an
error.

Define the macro in parse-options.h (if not already defined) so that
other tools can include it.
Signed-off-by: Josh Poimboeuf <jpoimboe@redhat.com>
Cc: "H. Peter Anvin" <hpa@zytor.com>
Cc: Andi Kleen <andi@firstfloor.org>
Cc: Andrew Morton <akpm@linux-foundation.org>
Cc: Andy Lutomirski <luto@kernel.org>
Cc: Bernd Petrovitsch <bernd@petrovitsch.priv.at>
Cc: Borislav Petkov <bp@alien8.de>
Cc: Chris J Arges <chris.j.arges@canonical.com>
Cc: Jiri Slaby <jslaby@suse.cz>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Michal Marek <mmarek@suse.cz>
Cc: Namhyung Kim <namhyung@gmail.com>
Cc: Pedro Alves <palves@redhat.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: live-patching@vger.kernel.org
Cc: x86@kernel.org
Link: http://lkml.kernel.org/r/6c16294ac6dbe5e2ca28fd935fe4389996588564.1450442274.git.jpoimboe@redhat.comSigned-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>

tools/lib/subcmd/parse-options.h

@@ -4,6 +4,10 @@
 #include <stdbool.h>
 #include <stdint.h>
 
+#ifndef NORETURN
+#define NORETURN __attribute__((__noreturn__))
+#endif
+
 enum parse_opt_type {
 	/* special types */
 	OPTION_END,