u-boot.mk: pass HOSTCC and HOST_CFLAGS into the build

Cuts build time on Mac OS X in half by avoiding repeated $(shell) calls
from the build system

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

include/u-boot.mk

@@ -40,6 +40,11 @@ endef
 
 TARGET_DEP = TARGET_$(BUILD_TARGET)$(if $(BUILD_SUBTARGET),_$(BUILD_SUBTARGET))
 
+UBOOT_MAKE_FLAGS = \
+	HOSTCC="$(HOSTCC)" \
+	HOSTCFLAGS='$(HOST_CFLAGS) $$$$(HOSTCPPFLAGS)' \
+	HOSTLDFLAGS=""
+
 define Build/U-Boot/Target
   $(eval $(call U-Boot/Init,$(1)))
   $(eval $(call U-Boot/Default,$(1)))

package/boot/uboot-lantiq/Makefile

@@ -366,6 +366,8 @@ define Build/Prepare
 	$(call CompressVR9Firmware,22f,2)
 endef
 
+UBOOT_MAKE_FLAGS :=
+
 ifeq ($(SUBTARGET),xway)
   SOC:=danube
 else