Simplify this further.

Thanks to Rui for noticing it.

llvm-svn: 299777
diff --git a/lld/ELF/LinkerScript.cpp b/lld/ELF/LinkerScript.cpp
index cd6093e..fdd6220 100644
--- a/lld/ELF/LinkerScript.cpp
+++ b/lld/ELF/LinkerScript.cpp
@@ -332,8 +332,7 @@
       continue;
 
     Cmd->Sections = computeInputSections(Cmd);
-    for (InputSectionBase *S : Cmd->Sections)
-      Ret.push_back(S);
+    Ret.insert(Ret.end(), Cmd->Sections.begin(), Cmd->Sections.end());
   }
 
   return Ret;