Clear windows branch; preserve previous contents in win-old

tools/windows/gpu_targets.generated.h.in

@@ -1,7 +0,0 @@
-#pragma once
-#include <array>
-namespace d4r::diag {
-struct GpuTarget { const char* architecture; unsigned elf_machine; unsigned isa_major; const char* family; };
-inline constexpr std::array<GpuTarget, @d4r_target_count@> gpu_targets = {{
-@d4r_target_cpp_entries@}};
-}