rules.mk: a little more robustness

rules.mk

@@ -31,8 +31,10 @@ ADK_TARGET_SUFFIX:=	$(strip $(subst ",, $(ADK_TARGET_SUFFIX)))
 ADK_COMPRESSION_TOOL:=	$(strip $(subst ",, $(ADK_COMPRESSION_TOOL)))
 
 ifeq ($(strip ${ADK_HAVE_DOT_CONFIG}),y)
+ifneq ($(strip $(wildcard $(TOPDIR)/target/$(ADK_TARGET)/target.mk)),)
 include $(TOPDIR)/target/$(ADK_TARGET)/target.mk
 endif
+endif
 
 include $(TOPDIR)/mk/vars.mk