Include exfat if source is present

Conflicts:
	base.mk

Change-Id: I870ba96f328885ef6908313ade43aa99a171b8a3
diff --git a/base.mk b/base.mk
index 8a7fc25..2f61913 100644
--- a/base.mk
+++ b/base.mk
@@ -76,3 +76,9 @@
 	device/phh/treble/device.rc:system/etc/init/device.rc \
 	device/phh/treble/change-device-name.sh:system/bin/change-device-name.sh
 	
+
+ifneq (,$(wildcard external/exfat)
+PRODUCT_PACKAGES += \
+	mkfs.exfat \
+	fsck.exfat
+endif