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

llvm-svn: 198957
diff --git a/clang/lib/Frontend/ASTUnit.cpp b/clang/lib/Frontend/ASTUnit.cpp
index 4f761f4..9830455 100644
--- a/clang/lib/Frontend/ASTUnit.cpp
+++ b/clang/lib/Frontend/ASTUnit.cpp
@@ -2591,8 +2591,7 @@
   }
 
   if (llvm::sys::fs::rename(TempPath.str(), File)) {
-    bool exists;
-    llvm::sys::fs::remove(TempPath.str(), exists);
+    llvm::sys::fs::remove(TempPath.str());
     return true;
   }