shader: link scalar leaf calls only for SWAPPC programs

Co-authored-by: Behzad <behzadkhan1736@gmail.com>

src/graphics/shader/recompiler/frontend/cfg/ShaderCFG.h

@@ -113,6 +113,9 @@ struct Graph {
 };
 
 Graph       BuildGraph(const Decoder::Program& program);
+bool MayWriteScalarRegister(const Decoder::Instruction& inst, uint32_t code);
+uint32_t FindScalarDefinition(const Decoder::Program& program, const Graph& graph,
+                              uint32_t before, uint32_t code);
 // Returns structured control flow or failure diagnostics without changing the native graph.
 // On failure, failure_block is an original block ID or UINT32_MAX.
 Graph       Structurize(const Graph& graph);