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

llvm-svn: 198957
diff --git a/clang/lib/Frontend/DependencyFile.cpp b/clang/lib/Frontend/DependencyFile.cpp
index 4037af9..1e3aba7 100644
--- a/clang/lib/Frontend/DependencyFile.cpp
+++ b/clang/lib/Frontend/DependencyFile.cpp
@@ -166,8 +166,7 @@
 
 void DependencyFileCallback::OutputDependencyFile() {
   if (SeenMissingHeader) {
-    bool existed;
-    llvm::sys::fs::remove(OutputFile, existed);
+    llvm::sys::fs::remove(OutputFile);
     return;
   }