Rename a local variable whose scope is very narrow. NFC.

llvm-svn: 331703
diff --git a/lld/ELF/LTO.cpp b/lld/ELF/LTO.cpp
index 90a0123..3a2220c 100644
--- a/lld/ELF/LTO.cpp
+++ b/lld/ELF/LTO.cpp
@@ -55,11 +55,11 @@
 }
 
 static void diagnosticHandler(const DiagnosticInfo &DI) {
-  SmallString<128> ErrStorage;
-  raw_svector_ostream OS(ErrStorage);
+  SmallString<128> S;
+  raw_svector_ostream OS(S);
   DiagnosticPrinterRawOStream DP(OS);
   DI.print(DP);
-  warn(ErrStorage);
+  warn(S);
 }
 
 static void checkError(Error E) {