perf data convert: Include config.h header

perf data convert: Include config.h header

Otherwise some compiler might scream:

  $ make LIBBABELTRACE_DIR=/opt/libbabeltrace/ LIBBABELTRACE=1
    BUILD:   Doing 'make -j4' parallel build
    CC       util/data-convert-bt.o
  util/data-convert-bt.c: In function ‘convert__config’:
  util/data-convert-bt.c:1299:19: error: implicit declaration of function ‘perf_config_u64’ [-Werror=implicit-function-declaration]
     c->queue_size = perf_config_u64(var, value);
  ...

Signed-off-by: Jiri Olsa <jolsa@kernel.org>
Cc: David Ahern <dsahern@gmail.com>
Cc: He Kuang <hekuang@huawei.com>
Cc: Marc Kleine-Budde <mkl@pengutronix.de>
Cc: Namhyung Kim <namhyung@kernel.org>
Cc: Peter Zijlstra <a.p.zijlstra@chello.nl>
Cc: Taeung Song <treeze.taeung@gmail.com>
Cc: Wang Nan <wangnan0@huawei.com>
Fixes: 41840d211c51 ("perf config: Move config declarations from util/cache.h to util/config.h")
Link: http://lkml.kernel.org/r/1466772025-17471-1-git-send-email-jolsa@kernel.org
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>