Add .travis.yml

.travis.yml in this commit means

 (1) Language is C.
 (2) Compiler is 'gcc'
 (3) Before testing, Travis-CI VM install 'gcc-multilib' for 32bit executables.
 (4) Travis-CI invokes 'make test'.

See also :

  Getting started
  http://docs.travis-ci.com/user/getting-started/

  Configuring your build
  http://docs.travis-ci.com/user/build-configuration/

  Building a C Project
  http://docs.travis-ci.com/user/build-configuration/

.travis.yml

@@ -0,0 +1,6 @@
+language: c
+compiler: gcc
+script: make test
+before_install:
+  - sudo apt-get update -qq
+  - sudo apt-get install -qq gcc-multilib