Simplify and correct variable assignments

- Remove asgnMaybeAppend, it was only used to indicate
  that the asignment needs a setDefault. But really, all
  types of variable assignments need setDefault if they're
  self-referential.
- Remove local_append/local_set_default because there was
  no implementation for them written in product_config.rbc
  anyways.
- Correct productConfigVariable.emitDefined using the global
  variables instead of the product config variables.
- Emit setDefaults for all types of assignments if they're
  self referential.

Bug: 222737841
Test: go test
Change-Id: I06a0f90f16d5900049d473281e6d5ef5e93e67da

mk2rbc/mk2rbc_test.go

@@ -898,6 +898,43 @@ def init(g, handle):
   cfg["PRODUCT_LIST1"] += ["c"]
   rblf.setdefault(handle, "PRODUCT_LIST2")
   cfg["PRODUCT_LIST2"] += ["c"]
+`,
+	},
+	{
+		desc:   "assigment setdefaults",
+		mkname: "product.mk",
+		in: `
+# All of these should have a setdefault because they're self-referential and not defined before
+PRODUCT_LIST1 = a $(PRODUCT_LIST1)
+PRODUCT_LIST2 ?= a $(PRODUCT_LIST2)
+PRODUCT_LIST3 += a
+
+# Now doing them again should not have a setdefault because they've already been set
+PRODUCT_LIST1 = a $(PRODUCT_LIST1)
+PRODUCT_LIST2 ?= a $(PRODUCT_LIST2)
+PRODUCT_LIST3 += a
+`,
+		expected: `# All of these should have a setdefault because they're self-referential and not defined before
+load("//build/make/core:product_config.rbc", "rblf")
+
+def init(g, handle):
+  cfg = rblf.cfg(handle)
+  rblf.setdefault(handle, "PRODUCT_LIST1")
+  cfg["PRODUCT_LIST1"] = (["a"] +
+      cfg.get("PRODUCT_LIST1", []))
+  if cfg.get("PRODUCT_LIST2") == None:
+    rblf.setdefault(handle, "PRODUCT_LIST2")
+    cfg["PRODUCT_LIST2"] = (["a"] +
+        cfg.get("PRODUCT_LIST2", []))
+  rblf.setdefault(handle, "PRODUCT_LIST3")
+  cfg["PRODUCT_LIST3"] += ["a"]
+  # Now doing them again should not have a setdefault because they've already been set
+  cfg["PRODUCT_LIST1"] = (["a"] +
+      cfg["PRODUCT_LIST1"])
+  if cfg.get("PRODUCT_LIST2") == None:
+    cfg["PRODUCT_LIST2"] = (["a"] +
+        cfg["PRODUCT_LIST2"])
+  cfg["PRODUCT_LIST3"] += ["a"]
 `,
 	},
 	{