Add update script for optionparser third party library

.gitattributes

@@ -15,3 +15,4 @@ data/* filter=lfs diff=lfs merge=lfs -text
 *.txt            whitespace=tab-in-indent
 
 vtkm/thirdparty/diy/vtkmdiy/**           -format.clang-format -whitespace
+vtkm/thirdparty/optionparser/vtkmoptionparser/** -format.clang-format -whitespace

vtkm/thirdparty/optionparser/update.sh

@@ -0,0 +1,25 @@
+#!/usr/bin/env bash
+
+set -e
+set -x
+shopt -s dotglob
+
+readonly name="optionparser"
+readonly ownership="Lean Mean C++ Option Parser Upstream <kwrobot@kitware.com>"
+readonly subtree="vtkm/thirdparty/$name/vtkm$name"
+readonly repo="https://gitlab.kitware.com/third-party/$name.git"
+readonly tag="for/vtk-m"
+readonly paths="
+src/optionparser.h
+"
+
+extract_source () {
+    git_archive
+
+    # The archive has sources in a src directory, but it is a header-only
+    # library. Just put the headers in the base directory for easier include.
+    mv "${extractdir}/${name}-reduced/src"/* "${extractdir}/${name}-reduced"
+    rmdir "${extractdir}/${name}-reduced/src"
+}
+
+. "${BASH_SOURCE%/*}/../update-common.sh"