perf trace: Extract the comm/tid printing for syscall enter

perf trace: Extract the comm/tid printing for syscall enter

Will be used with augmented syscalls, where we haven't transitioned
completely to combining sys_enter_FOO with sys_exit_FOO, so we'll go
as far as having it similar to the end result, strace like, as possible.

Cc: Adrian Hunter <adrian.hunter@intel.com>
Cc: David Ahern <dsahern@gmail.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-canomaoiybkswwnhj69u9ae4@git.kernel.org
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>