Include FormatVariadic.h for formatv declaration.

Author: bader

clang/tools/clang-sycl-linker/ClangSYCLLinker.cpp

@@ -35,6 +35,7 @@
 #include "llvm/Option/Option.h"
 #include "llvm/Support/CommandLine.h"
 #include "llvm/Support/FileSystem.h"
+#include "llvm/Support/FormatVariadic.h"
 #include "llvm/Support/InitLLVM.h"
 #include "llvm/Support/Path.h"
 #include "llvm/Support/Program.h"