Travis: only do sdist with cabal != 1.16.

.travis.yml

@@ -25,15 +25,14 @@ install:
  - cabal-$CABALVER update
 # - git clone https://github.com/jgm/pandoc-types && cd pandoc-types && cabal-1.18 install && cd ..
  - cabal-$CABALVER install $JOPTS --only-dependencies --enable-tests
-# hsb2hs is needed for -fembed_data_files, and is needed for sdist on
-# older cabal versions (1.16):
- - cabal-$CABALVER install hsb2hs
 
 # Here starts the actual work to be performed for the package under test; any command which exits with a non-zero exit code causes the build to fail.
 script:
- - cabal-$CABALVER configure --enable-tests # needed for sdist with ghc 7.4.2/cabal 1.16
- - cabal-$CABALVER sdist --output-directory=build
- - cd build
+ - |
+   if [ "${CABALVER}" != "1.16" ]; then
+      cabal-$CABALVER sdist --output-directory=build
+      cd build
+   fi
  - cabal-$CABALVER configure --enable-tests -v2  # -v2 provides useful information for debugging
  - cabal-$CABALVER build $JOPTS --ghc-options=$GHCOPTS # this builds all libraries and executables (including tests/benchmarks)
  - cabal-$CABALVER test