[libFuzzer] fix minor inefficiency, PR24584

llvm-svn: 246087
diff --git a/llvm/lib/Fuzzer/FuzzerIO.cpp b/llvm/lib/Fuzzer/FuzzerIO.cpp
index f0295e9..a68c6c5 100644
--- a/llvm/lib/Fuzzer/FuzzerIO.cpp
+++ b/llvm/lib/Fuzzer/FuzzerIO.cpp
@@ -32,7 +32,7 @@
                                                long *Epoch) {
   std::vector<std::string> V;
   if (Epoch) {
-    auto E = GetEpoch(Dir.c_str());
+    auto E = GetEpoch(Dir);
     if (*Epoch >= E) return V;
     *Epoch = E;
   }