perf annotate: Use ops->target.name when available for unresolved call targets

There is a bug where when using 'perf annotate timerqueue_add' the
target for its only routine called with the 'callq' instruction,
'rb_insert_color', doesn't get resolved from its address when parsing
that 'callq' instruction.

That symbol resolution works when using 'perf report --tui' and then
doing annotation for 'timerqueue_add' from there, the vmlinux
dso->symbols rb_tree somehow gets in a state that we can't find that
address, that is a bug that has to be further investigated.

But since the objdump output has the function name, i.e. the raw objdump
disassembled line looks like:

So, before:

  # perf annotate timerqueue_add

              │      mov    %rbx,%rdi
              │      mov    %rbx,(%rdx)
              │    → callq  *ffffffff8184dc80
              │      mov    0x8(%rbp),%rdx
              │      test   %rdx,%rdx
              │    ↓ je     67

  # perf report

              │      mov    %rbx,%rdi
              │      mov    %rbx,(%rdx)
              │    → callq  rb_insert_color
              │      mov    0x8(%rbp),%rdx
              │      test   %rdx,%rdx
              │    ↓ je     67

And after both look the same:

  # perf annotate timerqueue_add

              │      mov    %rbx,%rdi
              │      mov    %rbx,(%rdx)
              │    → callq  rb_insert_color
              │      mov    0x8(%rbp),%rdx
              │      test   %rdx,%rdx
              │    ↓ je     67

From 'perf report' one can annotate and navigate to that 'rb_insert_color'
function, but not directly from 'perf annotate timerqueue_add', that
remains to be investigated and fixed.

Cc: Adrian Hunter <adrian.hunter@intel.com>
Cc: Andi Kleen <ak@linux.intel.com>
Cc: David Ahern <dsahern@gmail.com>
Cc: Jin Yao <yao.jin@linux.intel.com>
Cc: Jiri Olsa <jolsa@kernel.org>
Cc: Namhyung Kim <namhyung@kernel.org>
Cc: Wang Nan <wangnan0@huawei.com>
Link: https://lkml.kernel.org/n/tip-nkktz6355rhqtq7o8atr8f8r@git.kernel.org
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>

tools/perf/util/annotate.c

@@ -238,6 +238,9 @@ static int call__scnprintf(struct ins *ins, char *bf, size_t size,
 	if (ops->target.addr == 0)
 		return ins__raw_scnprintf(ins, bf, size, ops);
 
+	if (ops->target.name)
+		return scnprintf(bf, size, "%-6s %s", ins->name, ops->target.name);
+
 	return scnprintf(bf, size, "%-6s *%" PRIx64, ins->name, ops->target.addr);
 }