updater: Output msg when recovery is called

Output messages in log when recovery is attempted or succeeded during
incremental OTA update.

Change-Id: I4033df7ae3aaecbc61921d5337eda26f79164fda
(cherry picked from commit b686ba2114)

updater/blockimg.cpp

@@ -1670,6 +1670,9 @@ Value* BlockImageRecoverFn(const char* name, State* state, int argc, Expr* argv[
         return StringValue(strdup(""));
     }
 
+    // Output notice to log when recover is attempted
+    fprintf(stderr, "%s image corrupted, attempting to recover...\n", filename->data);
+
     // When opened with O_RDWR, libfec rewrites corrupted blocks when they are read
     fec::io fh(filename->data, O_RDWR);
 
@@ -1720,7 +1723,7 @@ Value* BlockImageRecoverFn(const char* name, State* state, int argc, Expr* argv[
             //     read and check if the errors field value has increased.
         }
     }
-
+    fprintf(stderr, "...%s image recovered successfully.\n", filename->data);
     return StringValue(strdup("t"));
 }