vendor._lattice_ice40: add an icepack_opts override

Add an icepack_opts override in case the user wants to pass
extra options to icepack as part of the build process.

Author: crzwdjk

amaranth/vendor/_lattice_ice40.py

@@ -160,6 +160,7 @@ class LatticeICE40Platform(TemplatedPlatform):
         r"""
         {{invoke_tool("icepack")}}
             {{verbose("-v")}}
+            {{get_override("icepack_opts")|options}}
             {{name}}.asc
             {{name}}.bin
         """

docs/changes.rst

@@ -125,6 +125,7 @@ Platform integration changes
 
 .. currentmodule:: amaranth.vendor
 
+* Added: ``icepack_opts`` override in :class:`vendor.LatticeICE40Platform`.
 * Added: ``OSCH`` as ``default_clk`` clock source in :class:`vendor.LatticeMachXO2Platform`, :class:`vendor.LatticeMachXO3LPlatform`.
 * Added: Xray toolchain support in :class:`vendor.XilinxPlatform`.
 * Added: :class:`vendor.GowinPlatform`.