Prep D8 default instead of CompatDX in build/soong

Bug: 69329508
Test: m checkbuild tests
Change-Id: Ibaa2d787c644cf25104af78305a6eed16028dcf0
diff --git a/java/config/makevars.go b/java/config/makevars.go
index 5c8589e..c382cc1 100644
--- a/java/config/makevars.go
+++ b/java/config/makevars.go
@@ -46,12 +46,14 @@
 	ctx.Strict("JAVADOC", "${JavadocCmd}")
 	ctx.Strict("COMMON_JDK_FLAGS", "${CommonJdkFlags}")
 
-	if ctx.Config().IsEnvTrue("USE_D8_DESUGAR") {
+	if ctx.Config().UseD8Desugar() {
 		ctx.Strict("DX", "${D8Cmd}")
 		ctx.Strict("DX_COMMAND", "${D8Cmd} -JXms16M -JXmx2048M")
+		ctx.Strict("USE_D8_DESUGAR", "true")
 	} else {
 		ctx.Strict("DX", "${DxCmd}")
 		ctx.Strict("DX_COMMAND", "${DxCmd} -JXms16M -JXmx2048M")
+		ctx.Strict("USE_D8_DESUGAR", "false")
 	}
 
 	ctx.Strict("TURBINE", "${TurbineJar}")