system: vold: Ensure a default vold.conf exists for generic target

Signed-off-by: San Mehat <san@google.com>
diff --git a/rootdir/Android.mk b/rootdir/Android.mk
index db98fab..779f2a9 100644
--- a/rootdir/Android.mk
+++ b/rootdir/Android.mk
@@ -8,6 +8,10 @@
 	etc/init.goldfish.sh \
 	etc/hosts
 
+ifeq ($(TARGET_PRODUCT),generic)
+copy_from := etc/vold.conf
+endif
+
 copy_to := $(addprefix $(TARGET_OUT)/,$(copy_from))
 copy_from := $(addprefix $(LOCAL_PATH)/,$(copy_from))