perf tools: Move dso_* related functions into dso object

Moving dso_* related functions into dso object.

Keeping symbol loading related functions still in the symbol object as
it seems more convenient.

Signed-off-by: Jiri Olsa <jolsa@redhat.com>
Reviewed-by: Namhyung Kim <namhyung@kernel.org>
Tested-by: Namhyung Kim <namhyung@kernel.org>
Cc: Corey Ashford <cjashfor@linux.vnet.ibm.com>
Cc: Frederic Weisbecker <fweisbec@gmail.com>
Cc: Ingo Molnar <mingo@elte.hu>
Cc: Namhyung Kim <namhyung@kernel.org>
Cc: Paul Mackerras <paulus@samba.org>
Cc: Peter Zijlstra <a.p.zijlstra@chello.nl>
Link: http://lkml.kernel.org/r/1351372712-21104-6-git-send-email-jolsa@redhat.com


[ committer note: Use "symbol.h" instead of <symbol.h> to make it build with O= ]
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>