[LLD][ELF] - Remove dead code. NFC.

I believe this line was dead after r362356.

git-svn-id: https://llvm.org/svn/llvm-project/lld/trunk@362367 91177308-0d34-0410-b5e6-96231b3b80d8
diff --git a/ELF/LinkerScript.cpp b/ELF/LinkerScript.cpp
index 3f68e6e..71c8ff2 100644
--- a/ELF/LinkerScript.cpp
+++ b/ELF/LinkerScript.cpp
@@ -481,7 +481,6 @@
       if (Sec->Name == "/DISCARD/") {
         discard(V);
         Sec->SectionCommands.clear();
-        Sec->SectionIndex = 0; // Not an orphan.
         continue;
       }