[build] first pass at multiarch support

Changing bonnibel to respect the --arch flag to configure. This requires
some reworking of modules, mostly in the addition of the ModuleList
class instead of just a dict of modules.

scripts/bonnibel/config.py

@@ -43,10 +43,10 @@ def _make_ninja_config(outfile, config, files):
             build.variable(k, v)
 
  
-def generate_configs(root, output, config, targets, kinds):
+def generate_configs(root, output, buildconfig, arch, targets, kinds):
 
-    assets = root / "assets" / "build"
-    base = ["global.yaml", f"config.{config}.yaml"]
+    assets = root / "assets" / "build" / arch
+    base = ["global.yaml", f"config.{buildconfig}.yaml"]
 
     depfiles = set()
 
@@ -65,4 +65,4 @@ def generate_configs(root, output, config, targets, kinds):
             outfile = output / target / f"config.{kind}.ninja"
             _make_ninja_config(outfile, config, files)
 
-    return depfiles
+    return depfiles