perf evsel: Move fprintf methods to separate source file

perf evsel: Move fprintf methods to separate source file

They still use functions that would drag more stuff to the python
binding, where these fprintf methods are not used, so separate it.

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: http://lkml.kernel.org/n/tip-xfp0mgq3hh3px61di6ixi1jk@git.kernel.org
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>