add vendor_boot image support

The vendor_boot partition is generated by mkbootimg and contains all the
device-specific information that used to reside in the boot partition.

Bug: 137297791
Change-Id: I5b005097b73f59857c3a2f92d693b3e67ee8424e
diff --git a/core/envsetup.mk b/core/envsetup.mk
index be22ff7..d06ba72 100644
--- a/core/envsetup.mk
+++ b/core/envsetup.mk
@@ -241,6 +241,7 @@
 _system_ext_path_placeholder := ||SYSTEM_EXT-PATH-PH||
 _odm_path_placeholder := ||ODM-PATH-PH||
 TARGET_COPY_OUT_VENDOR := $(_vendor_path_placeholder)
+TARGET_COPY_OUT_VENDOR_RAMDISK := vendor-ramdisk
 TARGET_COPY_OUT_PRODUCT := $(_product_path_placeholder)
 # TODO(b/135957588) TARGET_COPY_OUT_PRODUCT_SERVICES will copy the target to
 # product
@@ -849,6 +850,8 @@
 TARGET_RAMDISK_OUT_UNSTRIPPED := $(TARGET_OUT_UNSTRIPPED)
 TARGET_DEBUG_RAMDISK_OUT := $(PRODUCT_OUT)/$(TARGET_COPY_OUT_DEBUG_RAMDISK)
 
+TARGET_VENDOR_RAMDISK_OUT := $(PRODUCT_OUT)/$(TARGET_COPY_OUT_VENDOR_RAMDISK)
+
 TARGET_ROOT_OUT := $(PRODUCT_OUT)/$(TARGET_COPY_OUT_ROOT)
 TARGET_ROOT_OUT_BIN := $(TARGET_ROOT_OUT)/bin
 TARGET_ROOT_OUT_ETC := $(TARGET_ROOT_OUT)/etc