Add script to install gaisler rtems cross rc9

add-ons/install-gaisler-rcc-1.3-rc9.sh

+#!/bin/bash
+DIR="$( cd "$( dirname "${BASH_SOURCE[0]}" )" && pwd )"
+
+# shellcheck source=common.sh
+. "${DIR}/common.sh"
+
+DESCRIPTION="Gaisler's RCC1.3-rc9"
+PREFIX="/opt"
+INSTALL_PATH="$PREFIX/rcc-1.3.-rc9"
+URL="https://www.gaisler.com/anonftp/rcc/bin/linux/sparc-rtems-5-gcc-7.5.0-1.3-rc9-linux.txz"
+
+CheckTargetFolder "${DESCRIPTION}" "${INSTALL_PATH}"
+DownloadAndExtract "${DESCRIPTION}" "${URL}" "${PREFIX}" "J"