perf hist: Remove symbol.h from hist.h, just fwd decls are needed

To reduce the includes dependencies.

Cc: Adrian Hunter <adrian.hunter@intel.com>
Cc: Jiri Olsa <jolsa@kernel.org>
Cc: Namhyung Kim <namhyung@kernel.org>
Link: https://lkml.kernel.org/n/tip-cmvg5ght75mmfg1efeyna9rn@git.kernel.org
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>
4 files changed