[binutils] NFC: fix clang-tidy warning: use empty() instead of size() == 0

llvm-svn: 349710
diff --git a/llvm/tools/llvm-readobj/llvm-readobj.cpp b/llvm/tools/llvm-readobj/llvm-readobj.cpp
index ffc5845..f66564b 100644
--- a/llvm/tools/llvm-readobj/llvm-readobj.cpp
+++ b/llvm/tools/llvm-readobj/llvm-readobj.cpp
@@ -681,7 +681,7 @@
   }
 
   // Default to stdin if no filename is specified.
-  if (opts::InputFilenames.size() == 0)
+  if (opts::InputFilenames.empty())
     opts::InputFilenames.push_back("-");
 
   llvm::for_each(opts::InputFilenames, dumpInput);