On elf, undefined symbols can start with .L.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@114958 91177308-0d34-0410-b5e6-96231b3b80d8
diff --git a/lib/MC/ELFObjectWriter.cpp b/lib/MC/ELFObjectWriter.cpp
index 120789b..b60271f 100644
--- a/lib/MC/ELFObjectWriter.cpp
+++ b/lib/MC/ELFObjectWriter.cpp
@@ -689,12 +689,15 @@
     const MCSymbol &Symbol = it->getSymbol();
 
     // Ignore non-linker visible symbols.
-    if (!Asm.isSymbolLinkerVisible(Symbol))
+    if (!Asm.isSymbolLinkerVisible(Symbol) && !Symbol.isUndefined())
       continue;
 
     if (!it->isExternal() && !Symbol.isUndefined())
       continue;
 
+    if (Symbol.isVariable())
+      continue;
+
     uint64_t &Entry = StringIndexMap[Symbol.getName()];
     if (!Entry) {
       Entry = StringTable.size();