Allow library checks to fail for now. When we get better conformance we'll turn it back on as required.

.travis.yml

@@ -59,6 +59,10 @@ matrix:
     - env:
       - SCRIPT=ci_boost_library_check
 
+  allow_failures:
+    - env:
+      - SCRIPT=ci_boost_library_check
+
 before_install:
   # Fetch the scripts to do the actual building/testing.
   - |