PRODUCT_FULL_TREBLE disabled warning

Treble is like so 2016, but it's 2023.

Bug: 307369186
Test: build
Change-Id: Icb24e218d0dbc5f76f0c83f809728d33dc67719e
diff --git a/core/config.mk b/core/config.mk
index d5fec33..4d79e2b 100644
--- a/core/config.mk
+++ b/core/config.mk
@@ -804,6 +804,10 @@
     PRODUCT_FULL_TREBLE \
     PRODUCT_NOTICE_SPLIT \
 
+ifneq ($(PRODUCT_FULL_TREBLE),true)
+    $(warning This device does not have Treble enabled. This is unsafe.)
+endif
+
 $(KATI_obsolete_var $(foreach req,$(requirements),$(req)_OVERRIDE) \
     ,This should be referenced without the _OVERRIDE suffix.)