Apply clang-format universally.

* It is tough to contribute to a project that doesn't use a formatter,
* It is extra hard to contribute to a project which has configured the formatter, but ignores it for some files
* Code formatting makes it harder to hide obscure / weird bugs by accident or on purpose,

Let's rip the bandaid off?

Note that PRs currently in flight should be able to be merged relatively easily by applying `clang-format` to their tip prior to merge.

src/libexpr/print-ambiguous.cc

@@ -7,11 +7,7 @@ namespace nix {
 
 // See: https://github.com/NixOS/nix/issues/9730
 void printAmbiguous(
-    Value &v,
-    const SymbolTable &symbols,
-    std::ostream &str,
-    std::set<const void *> *seen,
-    int depth)
+    Value & v, const SymbolTable & symbols, std::ostream & str, std::set<const void *> * seen, int depth)
 {
     checkInterrupt();
 
@@ -100,4 +96,4 @@ void printAmbiguous(
     }
 }
 
-}
+} // namespace nix