We shouldn't use temporary variable in the build recipe.

Use $@ instead.

Change-Id: Ida0960a453b3701383a31f698c3163a297c4bce5
diff --git a/core/droiddoc.mk b/core/droiddoc.mk
index 03a5011..ce0c46e 100644
--- a/core/droiddoc.mk
+++ b/core/droiddoc.mk
@@ -160,7 +160,7 @@
 
 $(full_target): $(full_src_files) $(droiddoc_templates) $(droiddoc) $(html_dir_files) $(full_java_lib_deps) $(LOCAL_ADDITIONAL_DEPENDENCIES)
 	@echo Docs droiddoc: $(PRIVATE_OUT_DIR)
-	$(hide) mkdir -p $(dir $(full_target))
+	$(hide) mkdir -p $(dir $@)
 	$(call prepare-doc-source-list,$(PRIVATE_SRC_LIST_FILE),$(PRIVATE_JAVA_FILES), \
 			$(PRIVATE_SOURCE_INTERMEDIATES_DIR) $(PRIVATE_ADDITIONAL_JAVA_DIR))
 	$(hide) ( \
@@ -193,7 +193,7 @@
 ##
 $(full_target): $(full_src_files) $(full_java_lib_deps)
 	@echo Docs javadoc: $(PRIVATE_OUT_DIR)
-	@mkdir -p $(dir $(full_target))
+	@mkdir -p $(dir $@)
 	$(call prepare-doc-source-list,$(PRIVATE_SRC_LIST_FILE),$(PRIVATE_JAVA_FILES), \
 			$(PRIVATE_SOURCE_INTERMEDIATES_DIR) $(PRIVATE_ADDITIONAL_JAVA_DIR))
 	$(hide) ( \