Separate base packages from customizations

The `build.packages` and `install.packages` files in the CONFIGDIR now
only need to include *additional* packages to install.  The packages
*required* for Aimee OS are always installed, listed in the
corresponding files in the source directory.

Makefile

@@ -19,7 +19,7 @@ prepare: $(O)/.prepared
 
 $(O)/.host-tools: \
 		build-host-tools.sh \
-		$(CONFIGDIR)/host-tools.packages \
+		host-tools.packages \
 		$(shell find $(CONFIGDIR)/portage/host -type f) \
 		$(O)/.prepared
 	./build-host-tools.sh
@@ -29,6 +29,8 @@ host-tools: $(O)/.host-tools
 
 $(O)/.built: \
 		build.sh \
+		build.packages \
+		install.packages \
 		$(CONFIGDIR)/build.packages \
 		$(CONFIGDIR)/install.packages \
 		$(shell find $(CONFIGDIR)/portage/target -type f) \
@@ -39,6 +41,7 @@ $(O)/.built: \
 
 $(O)/.ready: \
 		build-rootfs.sh \
+		install.packages \
 		$(CONFIGDIR)/install.packages \
 		$(CONFIGDIR)/installonly.packages \
 		$(CONFIGDIR)/busybox.symlinks \