Make default features the default build again

For osx and windows targets build with the first env combination since
they are matrix includes. This ensures that this selects the build
script with default features instead of no features.

.travis.yml

@@ -18,6 +18,7 @@ env:
   global:
     - secure: "WI/r7hbDhenb7zPXht8J0mhcx5aUgY22cCrwYmNksMmgIK9hYfPjZ68XzaQ7+Ity8b12TlHM8lGRN9bIsyAZEiRIkxkZAArY9bXAOExJaAT+yOyxhEs/QdrGB6iRhC6FTxPwgUH82j0nFL1UI7HqBnOy3g3tv23jq1AlD9N3t0k="
   matrix:
+    - DEFAULT_FEATURES='yes'
     - FEATURES=''
     - FEATURES='gif_codec'
     - FEATURES='jpeg'
@@ -27,7 +28,6 @@ env:
     - FEATURES='tiff'
     - FEATURES='webp'
     - FEATURES='hdr'
-    - DEFAULT_FEATURES='yes'
 matrix:
   allow_failures:
     - name: "Clippy"