Move `deps.hpp` all into build/

src/dds/build/deps.hpp

 #pragma once
 
-#include <dds/toolchain/deps.hpp>
 #include <dds/util/fs.hpp>
 
 #include <string>
 
 namespace dds {
 
+enum class deps_mode {
+    none,
+    msvc,
+    gnu,
+};
+
+struct deps_info {
+    fs::path              output;
+    std::vector<fs::path> inputs;
+    std::string           command;
+    std::string           command_output;
+};
+
 class database;
 
 deps_info parse_mkfile_deps_file(path_ref where);

src/dds/build/plan/compile_file.hpp

 
 #include <dds/build/plan/base.hpp>
 #include <dds/source.hpp>
-#include <dds/toolchain/deps.hpp>
 
 #include <memory>
 

src/dds/toolchain/deps.hpp

-#pragma once
-
-#include <dds/util/fs.hpp>
-
-#include <vector>
-
-namespace dds {
-
-enum class deps_mode {
-    none,
-    msvc,
-    gnu,
-};
-
-struct deps_info {
-    fs::path              output;
-    std::vector<fs::path> inputs;
-    std::string           command;
-    std::string           command_output;
-};
-
-}  // namespace dds

src/dds/toolchain/prep.hpp

 #pragma once
 
-#include <dds/toolchain/deps.hpp>
+#include <dds/build/deps.hpp>
 
 #include <string>
 #include <vector>

src/dds/toolchain/toolchain.hpp

 #pragma once
 
-#include <dds/toolchain/deps.hpp>
+#include <dds/build/deps.hpp>
 #include <dds/util/fs.hpp>
 
 #include <optional>