Use llvm::utohexstr instead of Twine::utohexstr.

They are essentially the same in this context, so I prefer the one
that doesn't need `Twine::`.

llvm-svn: 287814
diff --git a/lld/ELF/Relocations.cpp b/lld/ELF/Relocations.cpp
index 3cdad5d..d9a62a6 100644
--- a/lld/ELF/Relocations.cpp
+++ b/lld/ELF/Relocations.cpp
@@ -556,8 +556,7 @@
     return SrcFile + ":(function " + maybeDemangle(Encl->getName()) + ")";
 
   // If there's no symbol, print out the offset instead of a symbol name.
-  return (SrcFile + ":(" + S.Name + "+0x" + Twine::utohexstr(Offset) + ")")
-      .str();
+  return (SrcFile + ":(" + S.Name + "+0x" + utohexstr(Offset) + ")").str();
 }
 
 template <class ELFT>