Add support for separate kernels for boot and recovery [1/2]

* Either as prebuilts, or with separate defconfigs

Change-Id: Iad877a5fbef095e3e5d792aebb240c230a829552

Author: marcost2

build/tasks/kernel.mk

@@ -227,9 +227,6 @@ else
     endif
 endif
 
-KERNEL_VENDOR_RAMDISK_DEPMOD_STAGING_DIR := $(KERNEL_BUILD_OUT_PREFIX)$(call intermediates-dir-for,PACKAGING,depmod_vendor_ramdisk)
-$(INTERNAL_VENDOR_RAMDISK_TARGET): $(TARGET_PREBUILT_INT_KERNEL)
-
 ifeq ($(or $(FULL_RECOVERY_KERNEL_BUILD), $(FULL_KERNEL_BUILD)),true)
 # Add host bin out dir to path
 PATH_OVERRIDE := PATH=$(KERNEL_BUILD_OUT_PREFIX)$(HOST_OUT_EXECUTABLES):$$PATH
@@ -402,19 +399,7 @@ $(KERNEL_ADDITIONAL_CONFIG_OUT): $(KERNEL_OUT)
 
 $(KERNEL_CONFIG): $(KERNEL_DEFCONFIG_SRC) $(KERNEL_ADDITIONAL_CONFIG_OUT)
 	@echo "Building Kernel Config"
-	$(call make-kernel-target,VARIANT_DEFCONFIG=$(VARIANT_DEFCONFIG) SELINUX_DEFCONFIG=$(SELINUX_DEFCONFIG) $(KERNEL_DEFCONFIG))
-	$(hide) if [ ! -z "$(KERNEL_CONFIG_OVERRIDE)" ]; then \
-			echo "Overriding kernel config with '$(KERNEL_CONFIG_OVERRIDE)'"; \
-			echo $(KERNEL_CONFIG_OVERRIDE) >> $(KERNEL_OUT)/.config; \
-			$(call make-kernel-target,oldconfig); \
-		fi
-	# Create defconfig build artifact
-	$(call make-kernel-target,savedefconfig)
-	$(hide) if [ ! -z "$(KERNEL_ADDITIONAL_CONFIG)" ]; then \
-			echo "Using additional config '$(KERNEL_ADDITIONAL_CONFIG)'"; \
-			$(KERNEL_SRC)/scripts/kconfig/merge_config.sh -m -O $(KERNEL_OUT) $(KERNEL_OUT)/.config $(KERNEL_SRC)/arch/$(KERNEL_ARCH)/configs/$(KERNEL_ADDITIONAL_CONFIG); \
-			$(call make-kernel-target,KCONFIG_ALLCONFIG=$(KERNEL_BUILD_OUT_PREFIX)$(KERNEL_OUT)/.config alldefconfig); \
-		fi
+	$(call make-kernel-config,$(KERNEL_OUT),$(KERNEL_DEFCONFIG))
 
 $(TARGET_PREBUILT_INT_KERNEL): $(KERNEL_CONFIG) $(DEPMOD) $(DTC)
 	@echo "Building Kernel Image ($(BOARD_KERNEL_IMAGE_NAME))"