[ELF2] Add support for -discard-none.

Differential Revision:	http://reviews.llvm.org/D13083

llvm-svn: 248499
diff --git a/lld/ELF/Writer.cpp b/lld/ELF/Writer.cpp
index 5946958..c9bf60e 100644
--- a/lld/ELF/Writer.cpp
+++ b/lld/ELF/Writer.cpp
@@ -336,7 +336,7 @@
       Elf_Sym_Range Syms = File.getLocalSymbols();
       for (const Elf_Sym &Sym : Syms) {
         ErrorOr<StringRef> SymName = Sym.getName(File.getStringTable());
-        if (SymName && !(Config->DiscardLocals && SymName->startswith(".L")))
+        if (SymName && SymTabSec.shouldKeepInSymtab(*SymName))
           SymTabSec.addSymbol(*SymName, true);
       }
     }