perf trace: Add option to show process COMM

perf trace: Add option to show process COMM

Enabled by default, disable with --no-comm, e.g.:

 181.821 (0.001 ms): deja-dup-monit/10784 recvmsg(fd: 8, msg: 0x7fff4342baf0, flags: PEEK|TRUNC|CMSG_CLOEXEC ) = 20
 181.824 (0.001 ms): deja-dup-monit/10784 geteuid(                                                           ) = 1000
 181.825 (0.001 ms): deja-dup-monit/10784 getegid(                                                           ) = 1000
 181.834 (0.002 ms): deja-dup-monit/10784 recvmsg(fd: 8, msg: 0x7fff4342baf0, flags: CMSG_CLOEXEC            ) = 20
 181.836 (0.001 ms): deja-dup-monit/10784 geteuid(                                                           ) = 1000
 181.838 (0.001 ms): deja-dup-monit/10784 getegid(                                                           ) = 1000
 181.705 (0.003 ms): evolution-addr/10924 recvmsg(fd: 10, msg: 0x7fff17dc6990, flags: PEEK|TRUNC|CMSG_CLOEXEC) = 1256
 181.710 (0.002 ms): evolution-addr/10924 geteuid(                                                           ) = 1000
 181.712 (0.001 ms): evolution-addr/10924 getegid(                                                           ) = 1000
 181.727 (0.003 ms): evolution-addr/10924 recvmsg(fd: 10, msg: 0x7fff17dc6990, flags: CMSG_CLOEXEC           ) = 1256
 181.731 (0.001 ms): evolution-addr/10924 geteuid(                                                           ) = 1000
 181.734 (0.001 ms): evolution-addr/10924 getegid(                                                           ) = 1000
 181.908 (0.002 ms): evolution-addr/10924 recvmsg(fd: 10, msg: 0x7fff17dc6990, flags: PEEK|TRUNC|CMSG_CLOEXEC) = 20
 181.913 (0.001 ms): evolution-addr/10924 geteuid(                                                           ) = 1000
 181.915 (0.001 ms): evolution-addr/10924 getegid(                                                           ) = 1000
 181.930 (0.003 ms): evolution-addr/10924 recvmsg(fd: 10, msg: 0x7fff17dc6990, flags: CMSG_CLOEXEC           ) = 20
 181.934 (0.001 ms): evolution-addr/10924 geteuid(                                                           ) = 1000
 181.937 (0.001 ms): evolution-addr/10924 getegid(                                                           ) = 1000
 220.718 (0.010 ms): at-spi2-regist/10715 sendmsg(fd: 3, msg: 0x7fffdb8756c0, flags: NOSIGNAL                ) = 200
 220.741 (0.000 ms): dbus-daemon/10711  ... [continued]: epoll_wait()) = 1
 220.759 (0.004 ms): dbus-daemon/10711 recvmsg(fd: 11, msg: 0x7ffff94594d0, flags: CMSG_CLOEXEC              ) = 200
 220.780 (0.002 ms): dbus-daemon/10711 recvmsg(fd: 11, msg: 0x7ffff94594d0, flags: CMSG_CLOEXEC              ) = 200
 220.788 (0.001 ms): dbus-daemon/10711 recvmsg(fd: 11, msg: 0x7ffff94594d0, flags: CMSG_CLOEXEC              ) = -1 EAGAIN Resource temporarily unavailable
 220.760 (0.004 ms): at-spi2-regist/10715 sendmsg(fd: 3, msg: 0x7fffdb8756c0, flags: NOSIGNAL                ) = 200
 220.771 (0.023 ms): perf/26347 open(filename: 0xf2e780, mode: 15918976                               ) = 19
 220.850 (0.002 ms): perf/26347 close(fd: 19                                                          ) = 0

Cc: Adrian Hunter <adrian.hunter@intel.com>
Cc: David Ahern <dsahern@gmail.com>
Cc: Frederic Weisbecker <fweisbec@gmail.com>
Cc: Jiri Olsa <jolsa@redhat.com>
Cc: Mike Galbraith <efault@gmx.de>
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-6be5jvnkdzjptdrebfn5263n@git.kernel.org
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>