Don't cabal check in travis, it doesn't like -O2

Author: dolio

.travis.yml

@@ -85,7 +85,7 @@ script:
  - cabal configure --enable-tests --enable-benchmarks -v2  # -v2 provides useful information for debugging
  - cabal build   # this builds all libraries and executables (including tests/benchmarks)
 # - cabal test
- - cabal check
+# - cabal check
  - cabal sdist   # tests that a source-distribution can be generated
 
 # Check that the resulting source distribution can be built & installed.