Temp travis fix

[angerman]

Please include the following checklist in your PR:

• Patches conform to the coding conventions.
• Any changes that could be relevant to users have been recorded in the changelog.
• The documentation has been updated, if necessary.
• If the change is docs-only, [ci skip] is used to avoid triggering the build bots.

Please also shortly describe how you tested your change. Bonus points for added tests!

alternative fix for #5123, #5126.

Fixes #5120.

[angerman]

Let's see if this really ugly hack, does the trick.

[angerman]

Lovely:

Linking /Users/travis/build/haskell/cabal/dist-newstyle/build/x86_64-osx/ghc-7.10.3/happy-1.19.9/build/happy/happy ...
Configuring library for pretty-show-1.6.16..
Preprocessing library for pretty-show-1.6.16..
happy: /Users/travis/.cabal/share/x86_64-osx-ghc-7.10.3/happy-1.19.9/HappyTemplate-arrays-coerce: openFile: does not exist (No such file or directory)
cabal: Failed to build pretty-show-1.6.16 (which is required by
cabal-install-2.1.0.0).

For the (macOS, 7.10.3, script) config.

Still trying to reproduce this locally...

[angerman]

So the reason for the above issue is #5104.

We build and link happy-1.19.9; and expect the happy on path to be 1.19.9 as well, which
of course is not a given.

[angerman]

@23Skidoo, all green! Unborked!

[23Skidoo]

Thanks a lot! Merged manually in 22330fc.