Make javac checkbuilds match jack

Building all java to dex is very slow.  Make javac checkbuilds act
like jack checkbuilds and only build to class files for unused
modules, and add a java-dex target that can be used to build
everything to dex.

Bug: 33105206
Test: m -j checkbuild
Change-Id: Idcf9c9e0223b9dd88aaa53beb0cb50a230034b0f
Merged-In: Idcf9c9e0223b9dd88aaa53beb0cb50a230034b0f
(cherry picked from commit 9eff830fa2484d531b3af670c51b061958b97e58)
diff --git a/core/java.mk b/core/java.mk
index 9ee4231..b31e316 100644
--- a/core/java.mk
+++ b/core/java.mk
@@ -350,11 +350,7 @@
 LOCAL_CHECKED_MODULE := $(jack_check_timestamp)
 endif
 else
-ifeq ($(LOCAL_IS_STATIC_JAVA_LIBRARY),true)
 LOCAL_CHECKED_MODULE := $(full_classes_compiled_jar)
-else
-LOCAL_CHECKED_MODULE := $(built_dex)
-endif
 endif
 endif
 endif
@@ -665,6 +661,8 @@
 	$(hide) rm -f $(dir $@)/classes*.dex
 	$(hide) cp -fp $(dir $<)/classes*.dex $(dir $@)
 
+java-dex: $(built_dex)
+
 endif # !LOCAL_IS_STATIC_JAVA_LIBRARY
 
 findbugs_xml := $(intermediates.COMMON)/findbugs.xml