Add TARGET_USERIMAGES_USE_EXT4 to x86 to fix broken pdk build

Change-Id: If01cec346f25527e8431bdc77f15f2454afe318d
diff --git a/BoardConfig.mk b/BoardConfig.mk
index 9a93145..e86047d 100644
--- a/BoardConfig.mk
+++ b/BoardConfig.mk
@@ -19,3 +19,12 @@
 USE_OPENGL_RENDERER := true
 
 BOARD_USE_LEGACY_UI := true
+
+# PDK does not use ext4 image, but it is added here to prevent build break.
+TARGET_USERIMAGES_USE_EXT4 := true
+BOARD_SYSTEMIMAGE_PARTITION_SIZE := 576716800
+BOARD_USERDATAIMAGE_PARTITION_SIZE := 419430400
+BOARD_CACHEIMAGE_PARTITION_SIZE := 69206016
+BOARD_CACHEIMAGE_FILE_SYSTEM_TYPE := ext4
+BOARD_FLASH_BLOCK_SIZE := 512
+TARGET_USERIMAGES_SPARSE_EXT_DISABLED := true