Use the simpler version of sys::fs::remove when possible.

llvm-svn: 198958
diff --git a/llvm/lib/Support/GraphWriter.cpp b/llvm/lib/Support/GraphWriter.cpp
index 85be415..83aa255 100644
--- a/llvm/lib/Support/GraphWriter.cpp
+++ b/llvm/lib/Support/GraphWriter.cpp
@@ -87,8 +87,7 @@
       errs() << "Error: " << ErrMsg << "\n";
       return false;
     }
-    bool Existed;
-    sys::fs::remove(Filename, Existed);
+    sys::fs::remove(Filename);
     errs() << " done. \n";
   }
   else {