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/lib/DebugInfo/DWARFContext.cpp b/lib/DebugInfo/DWARFContext.cpp
index 7e4132f..aaae952 100644
--- a/lib/DebugInfo/DWARFContext.cpp
+++ b/lib/DebugInfo/DWARFContext.cpp
@@ -595,9 +595,8 @@
         uint64_t SymAddr = 0;
         // ELF relocations may need the symbol address
         if (Obj->isELF()) {
-          object::SymbolRef Sym;
-          reloc_i->getSymbol(Sym);
-          Sym.getAddress(SymAddr);
+          object::symbol_iterator Sym = reloc_i->getSymbol();
+          Sym->getAddress(SymAddr);
         }
 
         object::RelocVisitor V(Obj->getFileFormatName());