Ensure apps have APPS_DIR and DEPS_DIR defined

So they can use include files and other from other apps
when they're built directly, and that they use the same
deps directory.

plugins/bootstrap.mk

@@ -75,7 +75,12 @@ PROJECT = $p
 PROJECT_DESCRIPTION = New project
 PROJECT_VERSION = 0.1.0
 
-include $(call core_relpath,$(dir $(ERLANG_MK_FILENAME)),$(APPS_DIR)/app)/erlang.mk
+# Make sure we know where the applications are located.
+ROOT_DIR := $(call core_relpath,$(dir $(ERLANG_MK_FILENAME)),$(APPS_DIR)/app)
+APPS_DIR := ..
+DEPS_DIR := $(call core_relpath,$(DEPS_DIR),$(APPS_DIR)/app)
+
+include $$(ROOT_DIR)/erlang.mk
 endef
 
 define bs_app

test/core_deps.mk

@@ -297,6 +297,21 @@ core-deps-apps-dir-include-lib: build clean
 	$i "Distclean the application"
 	$t $(MAKE) -C $(APP) distclean $v
 
+	$i "Build in a subdirectory"
+	$t $(MAKE) -C $(APP)/deep/libs/boy_app $v
+
+	$i "Check that all compiled files exist (excluding the top-level app)"
+	$t ! test -f $(APP)/$(APP).d
+	$t ! test -f $(APP)/ebin/$(APP).app
+
+	$t test -f $(APP)/deep/libs/boy_app/boy_app.d
+	$t test -f $(APP)/deep/libs/boy_app/ebin/boy_app.app
+	$t test -f $(APP)/deep/libs/boy_app/ebin/boy.beam
+
+	$t test -f $(APP)/deep/libs/girl_app/girl_app.d
+	$t test -f $(APP)/deep/libs/girl_app/ebin/girl_app.app
+	$t test -f $(APP)/deep/libs/girl_app/ebin/girl.beam
+
 core-deps-apps-new-app: build clean
 
 	$i "Bootstrap a new OTP library named $(APP)"