Demangler: remove a dead function.

NFC

Author: eeckstein

include/swift/Demangling/Demangle.h

@@ -484,11 +484,6 @@ enum class OperatorKind {
   Infix,
 };
 
-/// Mangle an identifier using Swift's mangling rules.
-void mangleIdentifier(const char *data, size_t length,
-                      OperatorKind operatorKind, std::string &out,
-                      bool usePunycode = true);
-
 /// Remangle a demangled parse tree.
 std::string mangleNode(NodePointer root);
 

lib/Demangling/OldRemangler.cpp

@@ -116,15 +116,6 @@ static void mangleIdentifier(StringRef ident, OperatorKind operatorKind,
   }
 }
 
-void Demangle::mangleIdentifier(const char *data, size_t length,
-                                OperatorKind operatorKind,
-                                std::string &out, bool usePunycode) {
-  DemanglerPrinter printer;
-  ::mangleIdentifier(StringRef(data, length), operatorKind,
-                     usePunycode, printer);
-  out = std::move(printer).str();
-}
-
 namespace {
   struct DeepHasher {
     size_t value = 0;