[AST] Remove respectOriginallyDefinedIn parameter from mangleAnyDecl

This was always set to `true` except for USR mangling, where we already
have it set to `false` for IDE USRs. The other clients were:

- AutoDiff, which is just using the resulting string as a dictionary
key, so don't seem to have any preference.
- The ClangImporter, which always overrides `@_originallyDefinedIn`
anyway.

lib/APIDigester/ModuleAnalyzerNodes.cpp

@@ -1120,8 +1120,7 @@ static StringRef calculateMangledName(SDKContext &Ctx, ValueDecl *VD) {
     return Ctx.buffer(attr->Name);
   }
   Mangle::ASTMangler NewMangler(VD->getASTContext());
-  return Ctx.buffer(NewMangler.mangleAnyDecl(VD, true,
-                                    /*bool respectOriginallyDefinedIn*/true));
+  return Ctx.buffer(NewMangler.mangleAnyDecl(VD, /*addPrefix*/ true));
 }
 
 static StringRef calculateLocation(SDKContext &SDKCtx, Decl *D) {