[llvm-readobj/llvm-readelf] - Don't fail to dump the object if .dynsym has broken sh_link field.

This is https://bugs.llvm.org/show_bug.cgi?id=42215.

GNU readelf allows to dump the objects in that case,
but llvm-readobj/llvm-readelf reports an error and stops.

The patch fixes that.

Differential revision: https://reviews.llvm.org/D63074

llvm-svn: 362938
diff --git a/llvm/tools/llvm-readobj/ELFDumper.cpp b/llvm/tools/llvm-readobj/ELFDumper.cpp
index f41adae..295763f 100644
--- a/llvm/tools/llvm-readobj/ELFDumper.cpp
+++ b/llvm/tools/llvm-readobj/ELFDumper.cpp
@@ -1423,7 +1423,11 @@
         // This is only used (if Elf_Shdr present)for naming section in GNU
         // style
         DynSymtabName = unwrapOrError(Obj->getSectionName(&Sec));
-        DynamicStringTable = unwrapOrError(Obj->getStringTableForSymtab(Sec));
+
+        if (Expected<StringRef> E = Obj->getStringTableForSymtab(Sec))
+          DynamicStringTable = *E;
+        else
+          warn(E.takeError());
       }
       break;
     case ELF::SHT_SYMTAB_SHNDX: