build: remove package makefile overlay functionality

Recent attempts to use it have shown that it does not work properly
except for a few undocumented cases. It's better to remove this now to
avoid having more people fall into the same trap

Signed-off-by: Felix Fietkau <nbd@nbd.name>

include/package.mk

@@ -232,14 +232,7 @@ define Build/DefaultTargets
   endef
 endef
 
-define Build/IncludeOverlay
-  $(eval -include $(wildcard $(TOPDIR)/overlay/*/$(PKG_DIR_NAME).mk))
-  define Build/IncludeOverlay
-  endef
-endef
-
 define BuildPackage
-  $(Build/IncludeOverlay)
   $(eval $(Package/Default))
   $(eval $(Package/$(1)))
 

include/toplevel.mk

@@ -81,7 +81,7 @@ _ignore = $(foreach p,$(IGNORE_PACKAGES),--ignore $(p))
 prepare-tmpinfo: FORCE
 	@+$(MAKE) -r -s staging_dir/host/.prereq-build $(PREP_MK)
 	mkdir -p tmp/info
-	$(_SINGLE)$(NO_TRACE_MAKE) -j1 -r -s -f include/scan.mk SCAN_TARGET="packageinfo" SCAN_DIR="package" SCAN_NAME="package" SCAN_DEPS="$(TOPDIR)/include/package*.mk $(TOPDIR)/overlay/*/*.mk" SCAN_DEPTH=5 SCAN_EXTRA=""
+	$(_SINGLE)$(NO_TRACE_MAKE) -j1 -r -s -f include/scan.mk SCAN_TARGET="packageinfo" SCAN_DIR="package" SCAN_NAME="package" SCAN_DEPS="$(TOPDIR)/include/package*.mk" SCAN_DEPTH=5 SCAN_EXTRA=""
 	$(_SINGLE)$(NO_TRACE_MAKE) -j1 -r -s -f include/scan.mk SCAN_TARGET="targetinfo" SCAN_DIR="target/linux" SCAN_NAME="target" SCAN_DEPS="image/Makefile profiles/*.mk $(TOPDIR)/include/kernel*.mk $(TOPDIR)/include/target.mk" SCAN_DEPTH=2 SCAN_EXTRA="" SCAN_MAKEOPTS="TARGET_BUILD=1"
 	for type in package target; do \
 		f=tmp/.$${type}info; t=tmp/.config-$${type}.in; \