Handle relocations that don't point to symbols.

In ELF (as in MachO), not all relocations point to symbols. Represent this
properly by using a symbol_iterator instead of a SymbolRef. Update llvm-readobj
ELF's dumper to handle relocatios without symbols.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@183284 91177308-0d34-0410-b5e6-96231b3b80d8
diff --git a/tools/llvm-readobj/ELFDumper.cpp b/tools/llvm-readobj/ELFDumper.cpp
index 2427b7d..67bbafa 100644
--- a/tools/llvm-readobj/ELFDumper.cpp
+++ b/tools/llvm-readobj/ELFDumper.cpp
@@ -571,7 +571,6 @@
   SmallString<32> RelocName;
   int64_t Addend;
   StringRef SymbolName;
-  SymbolRef Symbol;
   if (Obj->getElfHeader()->e_type == ELF::ET_REL){
     if (error(RelI->getOffset(Offset))) return;
   } else {
@@ -580,8 +579,9 @@
   if (error(RelI->getType(RelocType))) return;
   if (error(RelI->getTypeName(RelocName))) return;
   if (error(getELFRelocationAddend(*RelI, Addend))) return;
-  if (error(RelI->getSymbol(Symbol))) return;
-  if (error(Symbol.getName(SymbolName))) return;
+  symbol_iterator Symbol = RelI->getSymbol();
+  if (Symbol != Obj->end_symbols() && error(Symbol->getName(SymbolName)))
+    return;
 
   if (opts::ExpandRelocs) {
     DictScope Group(W, "Relocation");