[llvm-objcopy] Consistently use createStringError instead of make_error<StringError>

This was requested in the review of D57006.

Also add missing quotes around symbol names in error messages.

Differential Revision: https://reviews.llvm.org/D57014

llvm-svn: 351799
diff --git a/llvm/tools/llvm-objcopy/COFF/Object.cpp b/llvm/tools/llvm-objcopy/COFF/Object.cpp
index fc87d9e..83435df 100644
--- a/llvm/tools/llvm-objcopy/COFF/Object.cpp
+++ b/llvm/tools/llvm-objcopy/COFF/Object.cpp
@@ -56,9 +56,8 @@
     for (const Relocation &R : Sec.Relocs) {
       auto It = SymbolMap.find(R.Target);
       if (It == SymbolMap.end())
-        return make_error<StringError>("Relocation target " + Twine(R.Target) +
-                                           " not found",
-                                       object_error::invalid_symbol_index);
+        return createStringError(object_error::invalid_symbol_index,
+                                 "Relocation target %zu not found", R.Target);
       It->second->Referenced = true;
     }
   }