Flag to enable jpg support

Builder using a custom theme may have need for this.  Add a flag to
easily enable jpg support.

Change-Id: Ica74f8cb1312d3193105f2201a5cf8073e2edc82
diff --git a/prebuilt/Android.mk b/prebuilt/Android.mk
index f1cdc90..dba1810 100644
--- a/prebuilt/Android.mk
+++ b/prebuilt/Android.mk
@@ -122,7 +122,9 @@
     RELINK_SOURCE_FILES += $(TARGET_OUT_SHARED_LIBRARIES)/libext4_utils.so
 endif
 RELINK_SOURCE_FILES += $(TARGET_OUT_SHARED_LIBRARIES)/libaosprecovery.so
-#RELINK_SOURCE_FILES += $(TARGET_OUT_SHARED_LIBRARIES)/libjpeg.so
+ifneq ($(TW_INCLUDE_JPEG),)
+    RELINK_SOURCE_FILES += $(TARGET_OUT_SHARED_LIBRARIES)/libjpeg.so
+endif
 ifeq ($(TWHAVE_SELINUX), true)
     RELINK_SOURCE_FILES += $(TARGET_OUT_SHARED_LIBRARIES)/libselinux.so
     ifneq ($(TARGET_USERIMAGES_USE_EXT4), true)