update build.sh

Former-commit-id: ec1488d6e4fecc756349dd88b056dda24b181b9a

cpp/build.sh

@@ -18,6 +18,7 @@ do
         case $arg in
              t)
                 BUILD_TYPE=$OPTARG # BUILD_TYPE
+                KNOWHERE_OPTS="${KNOWHERE_OPTS} -t $OPTARG"
                 ;;
              u)
                 echo "Build and run unittest cases" ;