stage1, stage2: initial modlists support

stage1's got prepare-modules target collecting
modules file snippets all over stage1/modules.d/
subdirectories within individual features.

stage2 now adds names of all the features going into
a particular image as snippet file suffix list so that
individual features don't have to register themselves
twice (as a feature and as a propagator modules.d
snippet carrier).

This is going to allow both "uncommon" modules getting
included with no problem (sin@ has wanted cifs ones
for quite some time, for example, and some want e.g.
infiniband modules) *and* to reduce the actual list
below the common mark as well (which is the case with
live-privacy image, for one).

And stage1 memory consumption does matter in some cases
as it's highly critical with no chance to use swap yet.

features.in/stage2/config.mk

@@ -2,6 +2,7 @@
 use/stage2: sub/stage1
 	@$(call add_feature)
 	@$(call add,STAGE1_PACKAGES,file make-initrd make-initrd-propagator propagator)
+	@$(call add,STAGE1_MODLISTS,$$(FEATURES))
 	@$(call xport,STAGE1_KCONFIG)
 
 use/stage2/kms:

sub.in/stage1/Makefile

@@ -33,7 +33,7 @@ ifneq "$(findstring stage2,$(SUBPROFILES))" ""	### assumes stage2 ~ propagator
 PROPAGATOR_VERSION = ALT Linux
 PROPAGATOR_MAR_MODULES = ./modules
 PROPAGATOR_INITFS = ./initfs
-BUILD_PROPAGATOR = build-propagator
+BUILD_PROPAGATOR = prepare-modules build-propagator
 endif
 endif
 
@@ -45,6 +45,10 @@ GLOBAL_SQUASHFS := $(SQUASHFS)
 
 -include $(sort $(wildcard lib/*.mk))
 
+prepare-modules:
+	@echo $(foreach V,$(STAGE1_MODLISTS),$(wildcard modules.d/??-$(V))) \
+	| xargs -r -- cat >> $(PROPAGATOR_MAR_MODULES)
+
 # scripts prepare bootloader configuration, too
 # NB: we pass tested squashfs options for sub.in/stage2/Makefile to include
 all: | debug prepare-workdir copy-tree run-scripts $(BUILD_PROPAGATOR) \