rules.mk: sync with OpenWrt, 2021.07

rules.mk

@@ -27,7 +27,7 @@ empty:=
 space:= $(empty) $(empty)
 comma:=,
 merge=$(subst $(space),,$(1))
-confvar=$(shell echo '$(foreach v,$(1),$(v)=$(subst ','\'',$($(v))))' | $(STAGING_DIR_HOST)/bin/mkhash md5)
+confvar=$(shell echo '$(foreach v,$(1),$(v)=$(subst ','\'',$($(v))))' | $(MKHASH) md5)
 strip_last=$(patsubst %.$(lastword $(subst .,$(space),$(1))),%,$(1))
 
 paren_left = (
@@ -323,6 +323,9 @@ TARGET_CXX:=$(TARGET_CROSS)g++
 KPATCH:=$(SCRIPT_DIR)/patch-kernel.sh
 SED:=$(STAGING_DIR_HOST)/bin/sed -i -e
 ESED:=$(STAGING_DIR_HOST)/bin/sed -E -i -e
+MKHASH:=$(STAGING_DIR_HOST)/bin/mkhash
+# MKHASH is used in /scripts, so we export it here.
+export MKHASH
 CP:=cp -fpR
 LN:=ln -sf
 XARGS:=xargs -r
@@ -396,6 +399,12 @@ else
     $(SCRIPT_DIR)/rstrip.sh
 endif
 
+NINJA = \
+	MAKEFLAGS="$(MAKE_JOBSERVER)" \
+	$(STAGING_DIR_HOST)/bin/ninja \
+		$(if $(findstring c,$(OPENWRT_VERBOSE)),-v) \
+		$(if $(MAKE_JOBSERVER),,-j1)
+
 ifeq ($(CONFIG_IPV6),y)
   DISABLE_IPV6:=
 else
@@ -456,7 +465,7 @@ endef
 # $(2) => If set, recurse into subdirectories
 define sha256sums
 	(cd $(1); find . $(if $(2),,-maxdepth 1) -type f -not -name 'sha256sums' -printf "%P\n" | sort | \
-		xargs -r $(STAGING_DIR_HOST)/bin/mkhash -n sha256 | sed -ne 's!^\(.*\) \(.*\)$$!\1 *\2!p' > sha256sums)
+		xargs -r $(MKHASH) -n sha256 | sed -ne 's!^\(.*\) \(.*\)$$!\1 *\2!p' > sha256sums)
 endef
 
 # file extension