Add build skeleton

.gitignore

+stage/

.gitlab-ci.yml

+include:
+  - project: 'alchemy/infrastructure/gitlab-ci-config'
+    file: '3p-library.yml'
+
+variables:
+  BUILD_COMMON: 1
+  BUILD_WINDOWS: 0
+  BUILD_WINDOWS64: 0
+  BUILD_LINUX64: 0
+  BUILD_MACOS: 0

autobuild.xml

+<?xml version="1.0" ?>
+<llsd>
+<map>
+    <key>package_description</key>
+    <map>
+      <key>canonical_repo</key>
+      <string>https://git.alchemyviewer.org/alchemy/thirdparty/llphysicsextensions_stub</string>
+      <key>copyright</key>
+      <string>Copyright (c) 2010, Linden Research, Inc.</string>
+      <key>license</key>
+      <string>internal</string>
+      <key>license_file</key>
+      <string>LICENSES/llphysicsextensions.txt</string>
+      <key>name</key>
+      <string>llphysicsextensions_stub</string>
+      <key>platforms</key>
+      <map>
+        <key>common</key>
+        <map>
+          <key>build_directory</key>
+          <string>stage</string>
+          <key>configurations</key>
+          <map>
+            <key>default</key>
+            <map>
+              <key>build</key>
+              <map>
+                <key>arguments</key>
+                <array>
+                  <string>../build-cmd.sh</string>
+                </array>
+                <key>command</key>
+                <string>sh</string>
+              </map>
+              <key>default</key>
+              <string>True</string>
+              <key>name</key>
+              <string>default</string>
+            </map>
+          </map>
+          <key>manifest</key>
+          <array>
+            <string>LICENSES/llphysicsextensions-LGPL-2.1.txt</string>
+            <string>include/llphysicsextensions/*</string>
+            <string>llphysicsextensions/stub/*</string>
+          </array>
+          <key>name</key>
+          <string>common</string>
+        </map>
+      </map>
+      <key>version_file</key>
+      <string>VERSION.txt</string>
+    </map>
+    <key>type</key>
+    <string>autobuild</string>
+    <key>version</key>
+    <string>1.3</string>
+  </map>
+</llsd>

build-cmd.sh

+#!/usr/bin/env bash
+
+# turn on verbose debugging output for logs.
+exec 4>&1; export BASH_XTRACEFD=4; set -x
+# make errors fatal
+set -e
+# bleat on references to undefined shell variables
+set -u
+
+echo "1.0" > VERSION.txt
+
+# this script should be executed from the build output directory (stage)
+cp -r "../include" "include/"
+cp -r "../LICENSES" "LICENSES/"
+cp -r "../llphysicsextensions" "llphysicsextensions/"