Add basic Travis CI config.

.travis.yml

@@ -0,0 +1,28 @@
+# Copyright 2019 Google Inc.
+#
+# 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
+#
+#      http://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.
+
+dist: xenial
+sudo: false
+language: c
+
+matrix:
+  include:
+    - os: linux
+      compiler: gcc
+    - os: linux
+      compiler: clang
+    - os: osx
+
+script:
+  - ./configure && make