setupvars and demos: Fix getting script dir on macOS 10.15 with with default zsh shell (#5094)

scripts/setupvars/setupvars.sh

@@ -3,7 +3,7 @@
 # Copyright (C) 2018-2021 Intel Corporation
 # SPDX-License-Identifier: Apache-2.0
 
-SCRIPT_DIR="$( cd "$( dirname "${BASH_SOURCE[0]}" )" >/dev/null 2>&1 && pwd )"
+SCRIPT_DIR="$( cd "$( dirname "${BASH_SOURCE[0]-$0}" )" >/dev/null 2>&1 && pwd )"
 BASE_DIR="$( dirname "$SCRIPT_DIR" )"
 
 INSTALLDIR="${BASE_DIR}"