Add osx build test to Travis

.travis-script.sh

@@ -2,7 +2,7 @@
 set -ev
 
 ./autogen.sh
-./configure
+./configure $KVZ_CONFIGURE_ARGS
 make --jobs=2 V=1
 
 if [ -n "$VALGRIND_TEST" ]; then

.travis.yml

@@ -45,6 +45,11 @@ matrix:
           - libtool
           - yasm
 
+    - os: osx
+      # The version of clang in the osx image complains about -pthread being given to linker.
+      # It's a silly warning and I don't know a workaround, so let's just ignore all warnings.
+      env: KVZ_CONFIGURE_ARGS="--disable-werror"
+
     # Check for external symbols without kvz_ prefix.
     - compiler: gcc-4.8
       script: