Arduino Pigweed Target

- New arduino pigweed target that uses gn build args to set arduino
  target board and specific build options.
- Add arduinobuilder.py (includes core installer for Linux/Mac/Windows)
- Working builds for Teensy 4.1, 4.0, 3.6, 3.5, 3.2

Change-Id: Ib751b5f92352ac3ec7fa649f444dc13efd080d12
Reviewed-on: https://pigweed-review.googlesource.com/c/pigweed/pigweed/+/18001
Commit-Queue: Anthony DiGirolamo <tonymd@google.com>
Reviewed-by: Armando Montanez <amontanez@google.com>
diff --git a/pw_sys_io_arduino/BUILD.gn b/pw_sys_io_arduino/BUILD.gn
new file mode 100644
index 0000000..159d7d2
--- /dev/null
+++ b/pw_sys_io_arduino/BUILD.gn
@@ -0,0 +1,42 @@
+# Copyright 2019 The Pigweed Authors
+#
+# Licensed under the Apache License, Version 2.0 (the "License"); you may not
+# use this file except in compliance with the License. You may obtain a copy of
+# the License at
+#
+#     https://www.apache.org/licenses/LICENSE-2.0
+#
+# Unless required by applicable law or agreed to in writing, software
+# distributed under the License is distributed on an "AS IS" BASIS, WITHOUT
+# WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. See the
+# License for the specific language governing permissions and limitations under
+# the License.
+
+# gn-format disable
+import("//build_overrides/pigweed.gni")
+
+import("$dir_pw_arduino_build/arduino.gni")
+import("$dir_pw_build/target_types.gni")
+import("$dir_pw_docgen/docs.gni")
+config("default_config") {
+  include_dirs = [ "public" ]
+}
+
+if (dir_pw_third_party_arduino != "") {
+  pw_source_set("pw_sys_io_arduino") {
+    remove_configs = [ "$dir_pw_build:strict_warnings" ]
+    public_configs = [ ":default_config" ]
+    public = [ "public/pw_sys_io_arduino/init.h" ]
+    public_deps = [ "$dir_pw_preprocessor" ]
+    deps = [
+      "$dir_pw_sys_io:default_putget_bytes",
+      "$dir_pw_sys_io:facade",
+      "$dir_pw_third_party_arduino:arduino_core_sources",
+    ]
+    sources = [ "sys_io_arduino.cc" ]
+  }
+}
+
+pw_doc_group("docs") {
+  sources = [ "docs.rst" ]
+}