AK: Turn off demangler in userland

For some reason, the default CXXFLAGS and such don't get us the
__cxa_demangle symbol in userland.

AK/Demangle.h

@@ -7,15 +7,18 @@ namespace AK {
 
 inline String demangle(const char* name)
 {
+#ifdef KERNEL
  int status = 0;
  auto* demangled_name = abi::__cxa_demangle(name, nullptr, nullptr, &status);
  auto string = String(status == 0 ? demangled_name : name);
  if (status == 0)
  kfree(demangled_name);
  return string;
+#else
+ return name;
+#endif
 }
 
 }
 
 using AK::demangle;
-