perf buildid-cache: Remove unneeded debugdir parameters

Functions related to buildid-cache subcommand use debugdir parameters
for passing buildid cache directory path. However all callers just pass
buildid_dir global variable. Moreover, other functions which refer
buildid cache use buildid_dir directly.

This removes unneeded debugdir parameters from those functions and use
buildid_dir if needed.

Signed-off-by: Masami Hiramatsu <masami.hiramatsu.pt@hitachi.com>
Acked-by: Namhyung Kim <namhyung@kernel.org>
Cc: Adrian Hunter <adrian.hunter@intel.com>
Cc: Borislav Petkov <bp@suse.de>
Cc: Hemant Kumar <hemant@linux.vnet.ibm.com>
Cc: Jiri Olsa <jolsa@kernel.org>
Cc: Paul Mackerras <paulus@samba.org>
Cc: Peter Zijlstra <a.p.zijlstra@chello.nl>
Link: http://lkml.kernel.org/r/20150210091851.19264.72741.stgit@localhost.localdomain
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>