pw_log: Logging module first steps

This starts a logging module facade, with a frontend and a dumb IO based
backend. The initial version is lacking many features, like an API to
control enabling or disabling logs.

Change-Id: I3075aed33d9600a1190ca5237b5f7cfcfdc8f2ed
diff --git a/pw_log_basic/BUILD b/pw_log_basic/BUILD
new file mode 100644
index 0000000..9430dd5
--- /dev/null
+++ b/pw_log_basic/BUILD
@@ -0,0 +1,26 @@
+# Copyright 2020 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.
+
+package(default_visibility = ["//visibility:public"])
+
+licenses(["notice"])  # Apache License 2.0
+
+filegroup(
+    name = "pw_log_basic",
+    srcs = [
+        "public/pw_log_basic/log_basic.h",
+        "public_overrides/pw_log_backend/log_backend.h",
+        "log_basic.cc",
+    ],
+)