[LLD] [ELF] Fix up a comment regarding the --wrap option. NFC.

[mstorsjo]

Summary

Add missing leading underscores to the __wrap_<symbol> and __real_<symbol> names.

The comments regarding the option also seem to use inconsistent spelling, both -wrap and --wrap occur - but I didn't change that bit here.

lld/ELF/Driver.cpp

       for (Symbol *sym : obj->getGlobalSymbols())
         sym->parseSymbolVersion();
     objectFiles.push_back(file);
   }
 }
 
 // The --wrap option is a feature to rename symbols so that you can write
 // wrappers for existing functions. If you pass `-wrap=foo`, all
-// occurrences of symbol `foo` are resolved to `wrap_foo` (so, you are
-// expected to write `wrap_foo` function as a wrapper). The original
-// symbol becomes accessible as `real_foo`, so you can call that from your
+// occurrences of symbol `foo` are resolved to `__wrap_foo` (so, you are
+// expected to write `__wrap_foo` function as a wrapper). The original
+// symbol becomes accessible as `__real_foo`, so you can call that from your
 // wrapper.
 //
 // This data structure is instantiated for each -wrap option.
 struct WrappedSymbol {
   Symbol *sym;
   Symbol *real;
   Symbol *wrap;
 };