Keep replace_instead_of_append in arch prop structs

replace_instead_of_append is read by proptools.ExtendProperties() /
proptools.ExtendMatchingProperties(). These functions are called on
arch property structs, so we need to preserve it when creating the
arch property structs.

Bug: 323382414
Test: m nothing --no-skip-soong-tests
Change-Id: Ic08704d8a2b710f5a5d99b62d3f8a37730bb6013
diff --git a/android/arch.go b/android/arch.go
index 3224c3a..cd8882b 100644
--- a/android/arch.go
+++ b/android/arch.go
@@ -975,12 +975,18 @@
 			panic(fmt.Errorf("unexpected tag format %q", field.Tag))
 		}
 		// these tags don't need to be present in the runtime generated struct type.
-		values = RemoveListFromList(values, []string{"arch_variant", "variant_prepend", "path", "replace_instead_of_append"})
+		// However replace_instead_of_append does, because it's read by the blueprint
+		// property extending util functions, which can operate on these generated arch
+		// property structs.
+		values = RemoveListFromList(values, []string{"arch_variant", "variant_prepend", "path"})
 		if len(values) > 0 {
-			panic(fmt.Errorf("unknown tags %q in field %q", values, prefix+field.Name))
+			if values[0] != "replace_instead_of_append" || len(values) > 1 {
+				panic(fmt.Errorf("unknown tags %q in field %q", values, prefix+field.Name))
+			}
+			field.Tag = `android:"replace_instead_of_append"`
+		} else {
+			field.Tag = ``
 		}
-
-		field.Tag = ``
 		return true, field
 	}
 	return false, field