perf session: Make read_build_id routines look at the host_machine too

The changes made to support host and guest machines in a session, that
started when the 'perf kvm' tool was introduced ended up introducing a
bug where the host_machine was not having its DSOs traversed for
build-id processing.

Fix it by moving some methods to the right classes and considering the
host_machine when processing build-ids.

Reported-by: Tom Zanussi <tzanussi@gmail.com>
Reported-by: Stephane Eranian <eranian@google.com>
Cc: Frédéric Weisbecker <fweisbec@gmail.com>
Cc: Mike Galbraith <efault@gmx.de>
Cc: Paul Mackerras <paulus@samba.org>
Cc: Peter Zijlstra <a.p.zijlstra@chello.nl>
Cc: Stephane Eranian <eranian@google.com>
Cc: Tom Zanussi <tzanussi@gmail.com>
LKML-Reference: <new-submission>
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>

tools/perf/util/session.c

@@ -895,3 +895,10 @@ size_t perf_session__fprintf_dsos(struct perf_session *self, FILE *fp)
 	       __dsos__fprintf(&self->host_machine.user_dsos, fp) +
 	       machines__fprintf_dsos(&self->machines, fp);
 }
+
+size_t perf_session__fprintf_dsos_buildid(struct perf_session *self, FILE *fp,
+					  bool with_hits)
+{
+	size_t ret = machine__fprintf_dsos_buildid(&self->host_machine, fp, with_hits);
+	return ret + machines__fprintf_dsos_buildid(&self->machines, fp, with_hits);
+}