Simplify swift::getInheritedForPrinting to take a PrintOptions

This lets us make some more assumptions in the next commit, but I
think it's also just a nice cleanup to /not/ allow random predicates
here.

There were three callers of this API:

- PrintAST, which was using PrintOptions::shouldPrint but /also/
  incorrectly notifying listeners that a declaration would be skipped.

- (IDE) Interface generation, which uses PrintOptions::shouldPrint to
  count how many "inherits" there will be.

- SwiftDocSupport's reportRelated, which does no filtering at all.
  Creating a PrintOptions here is a little more expensive, but still.

No intended functionality change.

tools/SourceKit/lib/SwiftLang/SwiftDocSupport.cpp

@@ -547,7 +547,7 @@ static void reportRelated(ASTContext &Ctx, const Decl *D,
     passInheritsAndConformancesForValueDecl(TAD, Consumer);
   } else if (const auto *TD = dyn_cast<TypeDecl>(D)) {
     llvm::SmallVector<TypeLoc, 4> AllInherits;
-    getInheritedForPrinting(TD, [](const Decl* d) { return true; }, AllInherits);
+    getInheritedForPrinting(TD, PrintOptions(), AllInherits);
     passInherits(AllInherits, Consumer);
     passConforms(TD->getSatisfiedProtocolRequirements(/*Sorted=*/true),
                  Consumer);