perf data ctf: Pass convert options through opts structure

Following commits will add new option to 'perf data convert'. All options
should be grouped into a structure and passed to low level converter
(currently there's only one converter).

Introduce data-convert.h and define 'struct perf_data_convert_opts' in
it. Pass 'force' through opts.

Signed-off-by: Wang Nan <wangnan0@huawei.com>
Acked-by: Jiri Olsa <jolsa@kernel.org>
Cc: Zefan Li <lizefan@huawei.com>
Cc: pi3orama@163.com
Link: http://lkml.kernel.org/r/1466767332-114472-3-git-send-email-wangnan0@huawei.com
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>