Use make variables to access java tools

Use make variables like $(JAVA) to access java tools in preparation
for moving java tools out of the path.

Test: builds
Bug: 62956999
Change-Id: I33b289e01318e7976c964b716ca78b564dba01dd
diff --git a/build/device_info_package.mk b/build/device_info_package.mk
index b91c264..4746e9c 100644
--- a/build/device_info_package.mk
+++ b/build/device_info_package.mk
@@ -49,7 +49,7 @@
 
 # Generator of APK manifests.
 MANIFEST_GENERATOR_JAR := $(HOST_OUT_JAVA_LIBRARIES)/compatibility-manifest-generator.jar
-MANIFEST_GENERATOR := java -jar $(MANIFEST_GENERATOR_JAR)
+MANIFEST_GENERATOR := $(JAVA) -jar $(MANIFEST_GENERATOR_JAR)
 
 # Generate the manifest
 manifest_xml := $(call intermediates-dir-for,APPS,$(LOCAL_PACKAGE_NAME))/AndroidManifest.xml