Makefile: enable target deps and native pkg build rules

Makefile

@@ -327,6 +327,21 @@ BUILD_PKGS := $(call set_create, \
             $(SED) -n 's,.*src/\(.*\)\.mk,\1,p'), \
         $(if $(value $(call LOOKUP_PKG_RULE,$(PKG),BUILD,$(BUILD))), $(PKG))))
 
+# create target sets for PKG_TARGET_RULE loop to avoid creating empty rules
+# and having to explicitly disable $(BUILD) for most packages
+CROSS_TARGETS := $(filter-out $(BUILD),$(MXE_TARGETS))
+$(foreach PKG,$(PKGS), \
+    $(foreach TARGET,$(or $(sort $($(PKG)_TARGETS)),$(CROSS_TARGETS)), \
+        $(eval $(TARGET)_PKGS += $(PKG)) \
+        $(eval FILTERED_PKGS  += $(PKG))))
+
+# cross targets depend on native target
+$(foreach TARGET,$(CROSS_TARGETS),\
+    $(eval $(TARGET)_DEPS = $(BUILD)))
+
+# always add $(BUILD) to our targets
+override MXE_TARGETS := $(CROSS_TARGETS) $(BUILD)
+
 # set column widths for build status messages
 PKG_COL_WIDTH    := $(call plus,2,$(call LIST_NMAX, $(sort $(call map, strlen, $(PKGS)))))
 MAX_TARGET_WIDTH := $(call LIST_NMAX, $(sort $(call map, strlen, $(MXE_TARGETS))))
@@ -394,6 +409,7 @@ $(PREFIX)/$(3)/installed/$(1): $(TOP_DIR)/src/$(1).mk \
                           $(PATCHES) \
                           $(wildcard $(TOP_DIR)/src/$(1)-test*) \
                           $(addprefix $(PREFIX)/$(3)/installed/,$(value $(call LOOKUP_PKG_RULE,$(1),DEPS,$(3)))) \
+                          $(and $($(3)_DEPS),$(addprefix $(PREFIX)/$($(3)_DEPS)/installed/,$($($(3)_DEPS)_PKGS))) \
                           | $(if $(DONT_CHECK_REQUIREMENTS),,check-requirements) \
                           $(if $(value $(call LOOKUP_PKG_RULE,$(1),URL,$(3))),download-only-$(1)) \
                           $(addprefix $(PREFIX)/$(3)/installed/,$(if $(call set_is_not_member,$(1),$(MXE_CONF_PKGS)),$(MXE_CONF_PKGS)))
@@ -456,7 +472,7 @@ build-only-$(1)_$(3):
 endef
 $(foreach TARGET,$(MXE_TARGETS), \
     $(shell [ -d '$(PREFIX)/$(TARGET)/installed' ] || mkdir -p '$(PREFIX)/$(TARGET)/installed') \
-    $(foreach PKG,$(PKGS), \
+    $(foreach PKG,$($(TARGET)_PKGS), \
         $(eval $(call PKG_TARGET_RULE,$(PKG),$(call TMP_DIR,$(PKG)-$(TARGET)),$(TARGET)))))
 
 # convenience set-like functions for unique lists
@@ -495,7 +511,7 @@ RECURSIVELY_EXCLUDED_PKGS = \
         $(call WALK_DOWNSTREAM,$(EXCLUDE_PKGS)))
 
 .PHONY: all-filtered
-all-filtered: $(filter-out $(call RECURSIVELY_EXCLUDED_PKGS),$(PKGS))
+all-filtered: $(filter-out $(call RECURSIVELY_EXCLUDED_PKGS),$(FILTERED_PKGS))
 
 # print a list of upstream dependencies and downstream dependents
 show-deps-%: