perf trace: Rename thread_thread->paths to thread_trace->files

perf trace: Rename thread_thread->paths to thread_trace->files

So that we can add more per file attributes besides the pathname, such
as which ioctl beautifier to use, for cases such as the sound and
usbdeffs ioctls, that both use the 'U' command, so we have to
differentiate at the major number for the device file.

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>
Link: https://lkml.kernel.org/n/tip-1895cmhrdz2dkl5prf2cj2yj@git.kernel.org
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>