perf callchain: Compare dsos (as well) for CCKEY_FUNCTION

Two functions from different binaries can have same start address. Thus,
comparing only start address in match_chain() leads to inconsistent
callchains. Fix this by adding a check for dsos as well.

Ex, https://www.spinics.net/lists/linux-perf-users/msg04067.html

Reported-by: Alexander Pozdneev <pozdneyev@gmail.com>
Signed-off-by: Ravi Bangoria <ravi.bangoria@linux.vnet.ibm.com>
Acked-by: Jiri Olsa <jolsa@kernel.org>
Cc: Alexander Shishkin <alexander.shishkin@linux.intel.com>
Cc: Andi Kleen <ak@linux.intel.com>
Cc: Krister Johansen <kjlx@templeofstupid.com>
Cc: Milian Wolff <milian.wolff@kdab.com>
Cc: Namhyung Kim <namhyung@kernel.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Yao Jin <yao.jin@linux.intel.com>
Cc: zhangmengting@huawei.com
Link: http://lkml.kernel.org/r/20171005091234.5874-1-ravi.bangoria@linux.vnet.ibm.com
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>