Remove use of showSDocUnsafe in extending_ghc.rst
There are lots of usages of showSDocUnsafe in extending_ghc.rst. However, they are all unnecessary as far as I could see because the Hsc or TcM context has a copy of DynFlags in it. It should be possible to replace them all with showSDoc.
Trac metadata
| Trac field | Value |
|---|---|
| Version | 8.4.3 |
| Type | Task |
| TypeOfFailure | OtherFailure |
| Priority | normal |
| Resolution | Unresolved |
| Component | Compiler |
| Test case | |
| Differential revisions | |
| BlockedBy | |
| Related | |
| Blocking | |
| CC | |
| Operating system | |
| Architecture |
