Project dependencies that call getDataFileName inside Template Haskell splices return paths that don’t exist

**Describe the bug**
This is a bit of a doozy. Credit to @rewinfrey for finding this out.

The https://github.com/github/semantic project depends on a package called https://github.com/tclem/lingo-haskell/, which provides autogenerated data structures that encapsulate the language information supported by https://github.com/github/linguist. This information is extracted from a YAML file of considerable length (just under 7,000 lines). Previously, we used a custom `Setup.hs` file to generate code with string concatenation; recently, because we wanted to support both `cabal` and `bazel`, we switched away from this rather ad-hoc approach, instead electing to read the file inside a Template Haskell splice and generate it appropriately, as per https://github.com/tclem/lingo-haskell/pull/9. In `cabal` builds, we get the file’s location [by invoking `getDataFileName`](https://github.com/tclem/lingo-haskell/blob/master/src/Data/Languages/Templates.hs#L52-L57) from the autogenerated `Paths_` library; under `bazel` we provide the path directly via a preprocessor directive. We published this revision as `lingo` 0.4.0.0; it builds fine both [on Hackage CI](https://matrix.hackage.haskell.org/#/package/lingo) and in local development within the `lingo-haskell` repository.

However, any packages that depend on this new revision fail to build. The error reported looks like so:

```
Building library for lingo-0.4.0.0..
[1 of 3] Compiling Paths_lingo ( dist/build/autogen/Paths_lingo.hs, dist/build/Paths_lingo.o, dist/build/Paths_lingo.dyn_o )
[2 of 3] Compiling Data.Languages.Templates ( src/Data/Languages/Templates.hs, dist/build/Data/Languages/Templates.o, dist/build/Data/Languages/Templates.dyn_o )
[3 of 3] Compiling Data.Languages ( src/Data/Languages.hs, dist/build/Data/Languages.o, dist/build/Data/Languages.dyn_o )

src/Data/Languages.hs:1:1: error:
Exception when trying to run compile-time code:
InvalidYaml (Just (YamlException "Yaml file not found: /Users/patrickt/.cabal/store/ghc-8.10.2/lng-0.4.0.0-bea0d472/share/languages.yml"))
Code: generateLanguageMap
|
1 | {-# LANGUAGE TemplateHaskell #-}
```

The `store` directory in question does not contain a `lng-0.4.0.0` directory, but `getDataFilePath` is reporting it as the correct path. For ease of reproducibility, I’ve attached [test-lingo.zip](https://github.com/haskell/cabal/files/5131735/test-lingo.zip), which is a bare project with a single `lingo` dependency.

**To Reproduce**
Steps to reproduce the behavior:

- download the file
- cd
- cabal v2-build

**Expected behavior**
Expected to build this dependency.

**System information**
- Darwin
- ghc 8.10.2
- cabal 3.2.0.0 (tested with 3.4.0.0-rc1 too)

**Additional context**
It’s possible that we may be doing something wrong w/r/t Hackage packaging of the `lingo` file; please let us know if this is the case. This is definitely an edge case, but if possible we’d like to keep these Template Haskell splices without having to generate .hs files ahead of time. We can work around this in client apps with some CPP directives, but it seems like a bug that `cabal` builds the `lingo` project itself correctly but not when it’s a dependency.