toolchains: Optionally build riscv-openocd with a separate script

.gitmodules

@@ -50,6 +50,9 @@
 [submodule "toolchains/riscv-tools/riscv-tests"]
 	path = toolchains/riscv-tools/riscv-tests
 	url = https://github.com/riscv/riscv-tests.git
+[submodule "toolchains/riscv-tools/riscv-openocd"]
+	path = toolchains/riscv-tools/riscv-openocd
+	url = https://github.com/riscv/riscv-openocd.git
 [submodule "vlsi/hammer"]
 	path = vlsi/hammer
 	url = https://github.com/ucb-bar/hammer.git

scripts/build-openocd.sh

@@ -0,0 +1,24 @@
+#!/usr/bin/env bash
+
+# exit script if any command fails
+set -e
+set -o pipefail
+
+RDIR=$(git rev-parse --show-toplevel)
+
+if [ -z "${RISCV}" ] ; then
+    ! [ -r "${RDIR}/env.sh" ] || . "${RDIR}/env.sh"
+    if [ -z "${RISCV}" ] ; then
+        echo "${0}: set the RISCV environment variable to desired install path"
+        exit 1
+    fi
+fi
+
+SRCDIR="${RDIR}/toolchains/riscv-tools"
+. "${RDIR}/scripts/build-util.sh"
+
+git config --unset submodule.toolchains/riscv-tools/riscv-openocd.update || :
+module_prepare riscv-openocd
+module_run riscv-openocd ./bootstrap
+module_build riscv-openocd --prefix="${RISCV}" \
+    --enable-remote-bitbang --enable-jtag_vpi --disable-werror