Add bash build script for both occlum-gcc and gcc

Signed-off-by: Zheng, Qi <huaiqing.zq@antgroup.com>

tools/toolchains/bash/build.sh

@@ -0,0 +1,34 @@
+#! /bin/bash
+set -e
+THIS_DIR="$( cd "$( dirname "${BASH_SOURCE[0]}"  )" >/dev/null 2>&1 && pwd )"
+INSTALL_DIR=/opt/occlum/toolchains/bash
+
+bash_source="https://github.com/occlum/bash.git"
+bash_branch="bash_5.1_for_occlum"
+
+rm -rf ${INSTALL_DIR}
+
+# Download bash source
+git clone -b ${bash_branch} ${bash_source}
+
+echo "Building bash with musl-gcc (occlum-gcc) ..."
+cd bash
+CC=occlum-gcc CXX=occlum-g++ ./configure --without-bash-malloc
+make clean
+make -j
+
+mkdir -p ${INSTALL_DIR}/musl
+cp bash ${INSTALL_DIR}/musl/
+
+# Restore code
+make clean
+git clean -dxf
+git reset HEAD --hard
+
+echo "Building bash with gcc ..."
+./configure
+make -j
+
+mkdir -p ${INSTALL_DIR}/glibc
+cp bash ${INSTALL_DIR}/glibc/
+