perf annotate browser: Compact 'nop' output

Just suppress the nop operands, future infrastructure that will record
the instruction lenght (and its contents) in struct ins will allow
rendering them as nopN, i.e. nop5 for a 5-byte nop.

Suggested-by: Linus Torvalds <torvalds@linux-foundation.org>
Cc: David Ahern <dsahern@gmail.com>
Cc: Frederic Weisbecker <fweisbec@gmail.com>
Cc: Mike Galbraith <efault@gmx.de>
Cc: Namhyung Kim <namhyung@gmail.com>
Cc: Paul Mackerras <paulus@samba.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Stephane Eranian <eranian@google.com>
Link: http://lkml.kernel.org/n/tip-qddbeglfzqdlal8vj2yaj67y@git.kernel.org
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>

tools/perf/util/annotate.c

@@ -113,6 +113,16 @@ bool ins__is_jump(const struct ins *ins)
 	return ins->ops == &jump_ops;
 }
 
+static int nop__scnprintf(struct ins *ins __used, char *bf, size_t size,
+			  struct ins_operands *ops __used)
+{
+	return scnprintf(bf, size, "%-6.6s", "nop");
+}
+
+static struct ins_ops nop_ops = {
+	.scnprintf = nop__scnprintf,
+};
+
 /*
  * Must be sorted by name!
  */
@@ -154,6 +164,9 @@ static struct ins instructions[] = {
 	{ .name = "jrcxz", .ops  = &jump_ops, },
 	{ .name = "js",	   .ops  = &jump_ops, },
 	{ .name = "jz",	   .ops  = &jump_ops, },
+	{ .name = "nop",   .ops  = &nop_ops, },
+	{ .name = "nopl",  .ops  = &nop_ops, },
+	{ .name = "nopw",  .ops  = &nop_ops, },
 };
 
 static int ins__cmp(const void *name, const void *insp)