perf beauty msg_flags: Add missing %s lost when adding prefix suppression logic

When the prefix suppresion/enabling logic was added, I forgot to add an
extra %, which ended up chopping off the strings:

Before:

  # perf trace -e *mmsg --map-dump syscalls
  [299] = 1,
  [307] = 1,
  DNS Res~ver #3/14587 sendmmsg(106<socket:[3462393]>, 0x7f252b0fcaf0, 2, MSG_) = 2
  chronyd/1053 recvmmsg(4, 0x558542ca5740, 4, MSG_, NULL) = 1
  DNS Res~ver #2/14445 sendmmsg(106<socket:[3461475]>, 0x7f252ab09af0, 2, MSG_) = 2
  DNS Res~ver #2/14444 sendmmsg(146<socket:[3457863]>, 0x7f2521a7aaf0, 2, MSG_) = 2
  DNS Res~ver #2/14445 sendmmsg(106<socket:[3461475]>, 0x7f252ab09af0, 2, MSG_) = 2
  DNS Res~ver #3/14587 sendmmsg(148<socket:[3460636]>, 0x7f252b0fcaf0, 2, MSG_) = 2
  DNS Res~ver #2/14444 sendmmsg(146<socket:[3457863]>, 0x7f2521a7aaf0, 2, MSG_) = 2
  ^C#

After:

  # perf trace -e *mmsg --map-dump syscalls
  [299] = 1,
  [307] = 1,
  NetworkManager/17467 sendmmsg(22<socket:[3466493]>, 0x7f28927f9bb0, 2, MSG_NOSIGNAL) = 2
  pool/17478 sendmmsg(10<socket:[3466523]>, 0x7f2769f95e90, 2, MSG_NOSIGNAL) = 2
  DNS Res~ver #3/14587 sendmmsg(121<socket:[3466132]>, 0x7f252b0fcaf0, 2, MSG_NOSIGNAL) = 2
  chronyd/1053 recvmmsg(4, 0x558542ca5740, 4, MSG_DONTWAIT, NULL) = 1
  Socket Thread/17433 sendmmsg(121<socket:[3460903]>, 0x7f252668baf0, 2, MSG_NOSIGNAL) = 2
  ^C#

Cc: Adrian Hunter <adrian.hunter@intel.com>
Cc: Jiri Olsa <jolsa@kernel.org>
Cc: Luis Cláudio Gonçalves <lclaudio@redhat.com>
Cc: Namhyung Kim <namhyung@kernel.org>
Cc: Wang Nan <wangnan0@huawei.com>
Fixes: c65c83ff ("perf trace: Allow asking for not suppressing common string prefixes")
Link: https://lkml.kernel.org/n/tip-t2eu1rqx710k6jr4814mlzg7@git.kernel.orgSigned-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>

tools/perf/trace/beauty/msg_flags.c

@@ -29,7 +29,7 @@ static size_t syscall_arg__scnprintf_msg_flags(char *bf, size_t size,
 		return scnprintf(bf, size, "NONE");
 #define	P_MSG_FLAG(n) \
 	if (flags & MSG_##n) { \
-		printed += scnprintf(bf + printed, size - printed, "%s%s", printed ? "|" : "", show_prefix ? prefix : "", #n); \
+		printed += scnprintf(bf + printed, size - printed, "%s%s%s", printed ? "|" : "", show_prefix ? prefix : "", #n); \
 		flags &= ~MSG_##n; \
 	}