Add an API to indicate the percentage progress of an rbu update.

FossilOrigin-Name: ffc58d2c2576a5b6e1c2c7112612c5760e711afd

ext/rbu/test_rbu.c

@@ -66,6 +66,7 @@ static int test_sqlite3rbu_cmd(
     {"create_rbu_delta", 2, ""},  /* 2 */
     {"savestate", 2, ""},         /* 3 */
     {"dbMain_eval", 3, "SQL"},    /* 4 */
+    {"stage_progress", 2, ""},    /* 5 */
     {0,0,0}
   };
   int iCmd;
@@ -136,6 +137,18 @@ static int test_sqlite3rbu_cmd(
       break;
     }
 
+    case 5: /* stage_progress */ {
+      int one, two;
+      Tcl_Obj *pObj;
+      sqlite3rbu_stage_progress(pRbu, &one, &two);
+
+      pObj = Tcl_NewObj();
+      Tcl_ListObjAppendElement(interp, pObj, Tcl_NewIntObj(one));
+      Tcl_ListObjAppendElement(interp, pObj, Tcl_NewIntObj(two));
+      Tcl_SetObjResult(interp, pObj);
+      break;
+    }
+
     default: /* seems unlikely */
       assert( !"cannot happen" );
       break;