Updated .travis.yml

.travis.yml

@@ -12,9 +12,18 @@ compiler:
 - gcc
 - clang
 
+env:
+  matrix:
+  - LIBTOOL=libtool
+  - LIBTOOL=libtool-disabled
+
 matrix:
   allow_failures:
   - os: osx
+
+before_install:
+  - if [[ "$TRAVIS_OS_NAME" == "osx" ]]; then brew update ; fi
+  - if [[ "$TRAVIS_OS_NAME" == "osx" ]]; then brew install libtool; fi
   
 script:
   - make