sdbusplus: use shorter type aliases

The sdbusplus headers provide shortened aliases for many types.
Switch to using them to provide better code clarity and shorter
lines.  Possible replacements are for:
  * bus_t
  * exception_t
  * manager_t
  * match_t
  * message_t
  * object_t
  * slot_t

Signed-off-by: Patrick Williams <patrick@stwcx.xyz>
Change-Id: Ib15ce49ac136da396084ab09972dd132f02beeea
diff --git a/test/test_snmp_serialize.cpp b/test/test_snmp_serialize.cpp
index 627045b..d291aae 100644
--- a/test/test_snmp_serialize.cpp
+++ b/test/test_snmp_serialize.cpp
@@ -22,7 +22,7 @@
 class TestSerialize : public testing::Test
 {
   public:
-    sdbusplus::bus::bus bus;
+    sdbusplus::bus_t bus;
     ConfManager manager;
     TestSerialize() :
         bus(sdbusplus::bus::new_default()),