Biggish refactor to break cycles; my build rules were full of them. cpm builds,

which requires top and topgen.

mach/i80/libend/build.lua

@@ -0,0 +1,8 @@
+for _, plat in ipairs(vars.plats) do
+	acklibrary {
+		name = "lib_"..plat,
+		srcs = { "./*.s" },
+		vars = { plat = plat },
+	}
+end
+