C preprocessor; tabgen; now the pc86 boot.s builds using the ack

toolchain.

util/cmisc/build.lua

@@ -0,0 +1,25 @@
+cprogram {
+	name = "tabgen",
+	srcs = { "./tabgen.c" }
+}
+
+definerule("tabgen",
+	{
+		srcs = { type="targets" },
+	},
+	function(e)
+		local symname = replace(basename(e.srcs[1]), "%.tab$", "")
+
+		return normalrule {
+			name = e.name,
+			ins = {
+				"util/cmisc+tabgen",
+				unpack(e.srcs)
+			},
+			outleaves = { symname..".c" },
+			commands = {
+				"%{ins[1]} -f%{ins[2]} > %{outs} || rm %{outs}"
+			}
+		}
+	end
+)