Enable R8 by default (sixth attempt)

Fixed bugs which was discovered in the last attempt.

Bug: 72373167
Bug: 72391662

Test: m -j PRODUCT-taimen-userdebug
Test: Check that some .vdex files built have R8 generated code
Change-Id: I89aaed9a4156748a513d6ee0284068b8a3c52322
diff --git a/core/config.mk b/core/config.mk
index 63ccbda..20acf34 100644
--- a/core/config.mk
+++ b/core/config.mk
@@ -556,7 +556,7 @@
 
 # Default R8 behavior when USE_R8 is not specified.
 ifndef USE_R8
-  USE_R8 := false
+  USE_R8 := true
 endif
 
 #