Disable building coverage with javac

Emma is unable to process framework.jar, and making framework
classes.jar depend on the emma output causes builds to fail when
emma is enabled.  Make classes.jar depend on the jarjar output
instead, bypassing emma for now.

Test: m -j EMMA_INSTRUMENT=true EMMA_INSTRUMENT_FRAMEWORK=true check-public-api
Change-Id: I861282292816e29ca27b67a3eef978d951c1a4dc
diff --git a/core/java.mk b/core/java.mk
index c2a4c83..eefcf2f 100644
--- a/core/java.mk
+++ b/core/java.mk
@@ -498,7 +498,8 @@
 endif
 
 # Keep a copy of the jar just before proguard processing.
-$(full_classes_jar): $(full_classes_emma_jar) | $(ACP)
+# TODO: this should depend on full_classes_emma_jar once coverage works again
+$(full_classes_jar): $(full_classes_jarjar_jar) | $(ACP)
 	@echo Copying: $@
 	$(hide) $(ACP) -fp $< $@