Added guard for some object inits to prevent memory leak by misuse (#662)

Co-authored-by: Nik Schewtschuk <nikonlinee@gmail.com>

src/bacnet/basic/object/ao.c

@@ -1279,5 +1279,7 @@ void Analog_Output_Cleanup(void)
  */
 void Analog_Output_Init(void)
 {
-    Object_List = Keylist_Create();
+    if (!Object_List) {
+        Object_List = Keylist_Create();
+    }
 }

src/bacnet/basic/object/blo.c

@@ -1554,5 +1554,7 @@ void Binary_Lighting_Output_Cleanup(void)
  */
 void Binary_Lighting_Output_Init(void)
 {
-    Object_List = Keylist_Create();
+    if (!Object_List) {
+        Object_List = Keylist_Create();
+    }
 }

src/bacnet/basic/object/bo.c

@@ -1231,5 +1231,7 @@ bool Binary_Output_Delete(uint32_t object_instance)
  */
 void Binary_Output_Init(void)
 {
-    Object_List = Keylist_Create();
+    if (!Object_List) {
+        Object_List = Keylist_Create();
+    }
 }

src/bacnet/basic/object/bv.c

@@ -1006,5 +1006,7 @@ bool Binary_Value_Delete(uint32_t object_instance)
  */
 void Binary_Value_Init(void)
 {
-    Object_List = Keylist_Create();
+    if (!Object_List) {
+        Object_List = Keylist_Create();
+    }
 }