Define proguard dictionary output for R8

When running with R8 instead of Proguard + dx the proguard mapping is
produced together with the dex output.

Bug: 68249935
Test: m -j ahat-test
Change-Id: Ica5ef455eb3bd1eabe55c43e9e026f47cadace1c
diff --git a/core/java.mk b/core/java.mk
index aa6331b..57e396b 100644
--- a/core/java.mk
+++ b/core/java.mk
@@ -719,7 +719,11 @@
 endif
 
 ifneq ($(filter obfuscation,$(LOCAL_PROGUARD_ENABLED)),)
+ifneq ($(USE_R8),true)
   $(full_classes_proguard_jar): .KATI_IMPLICIT_OUTPUTS := $(proguard_dictionary)
+else
+  $(built_dex_intermediate): .KATI_IMPLICIT_OUTPUTS := $(proguard_dictionary)
+endif
 endif
 
 # If R8 is not enabled run Proguard.