build/gowin/gowin: adding list of additional cst commands (to place resources)

Signed-off-by: Gwenhael Goavec-Merou <gwenhael@enjoy-digital.fr>

litex/build/gowin/gowin.py

@@ -26,6 +26,7 @@ class GowinToolchain(GenericToolchain):
     def __init__(self):
         super().__init__()
         self.options = {}
+        self.additional_cst_commands = []
 
     def finalize(self):
         if self.platform.verilog_include_paths:
@@ -108,6 +109,8 @@ class GowinToolchain(GenericToolchain):
         if self.named_pc:
             cst.extend(self.named_pc)
 
+        cst.extend(self.additional_cst_commands)
+
         tools.write_to_file(f"{self._build_name}.cst", "\n".join(cst))
         return (f"{self._build_name}.cst", "CST")