sdbus client: add retries

Handle busy responses from the server with retries.

Change-Id: I8c13faddec1bfaffe702609f2e682e8b1181946d
Signed-off-by: Brad Bishop <bradleyb@fuzziesquirrel.com>
diff --git a/libmapper/mapper.h b/libmapper/mapper.h
index b49b302..7459e15 100644
--- a/libmapper/mapper.h
+++ b/libmapper/mapper.h
@@ -1,4 +1,5 @@
 #include <systemd/sd-bus.h>
+#include <systemd/sd-event.h>
 
 #ifdef __cplusplus
 extern "C" {
@@ -6,9 +7,10 @@
 typedef struct mapper_async_wait mapper_async_wait;
 void mapper_wait_async_free(mapper_async_wait *);
 
-int mapper_wait_async(sd_bus *, char *[],
+int mapper_wait_async(sd_bus *, sd_event *, char *[],
 		void (*)(int, void *), void *, mapper_async_wait **);
 int mapper_get_service(sd_bus *conn, const char *obj, char **service);
+int mapper_get_object(sd_bus *conn, const char *obj, sd_bus_message **reply);
 #ifdef __cplusplus
 }
 #endif