Merge pull request #262 from omasanori/32bit

Build and test 32 & 64 bit builds on Travis CI.

.travis.yml

@@ -2,7 +2,12 @@ language: c
 compiler:
   - gcc
   - clang
+env:
+  - CFLAGS="-m32"
+  - CFLAGS="-m64"
 before_script:
+  - sudo apt-get update -qq
+  - sudo apt-get install -y libc6:i386 libgcc1:i386 gcc-4.6-base:i386 gcc-multilib
   - cd build
 script:
   - perl --version