Add pw_dumb_io with host backend

This change introduces the pw_dumb_io module, a module intended for
pigweed testing and bringup. pw_dumb_io includes a facade, and a backend
implementation using stdio (pw_dumb_io_stdio).

Change-Id: I5d9ca3c256c7e7c6d60cc07292aaead808a7f3dd
diff --git a/pw_dumb_io_stdio/BUILD.gn b/pw_dumb_io_stdio/BUILD.gn
new file mode 100644
index 0000000..8c1b875
--- /dev/null
+++ b/pw_dumb_io_stdio/BUILD.gn
@@ -0,0 +1,24 @@
+# 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.
+
+source_set("pw_dumb_io_stdio") {
+  public_configs = [ "$dir_pw_build:pw_default_cpp" ]
+  deps = [
+    "$dir_pw_dumb_io:default_putget_bytes",
+    "$dir_pw_dumb_io:facade",
+  ]
+  sources = [
+    "dumb_io.cc",
+  ]
+}