image.mk: make image too big warnings more visible

Output warnings through stderr to allow them to be easilier spotted
when building with V=w.

Signed-off-by: Jonas Gorski <[email protected]>

SVN-Revision: 45746

include/image.mk

@@ -321,7 +321,7 @@ endef
 
 define Build/check-size
 	@[ $$(($(subst k,* 1024,$(subst m, * 1024k,$(1))))) -gt "$$(stat -c%s $@)" ] || { \
-		echo "WARNING: Image file $@ is too big"; \
+		echo "WARNING: Image file $@ is too big" >&2; \
 		rm -f $@; \
 	}
 endef
@@ -378,7 +378,7 @@ endif
 
 define Device/Build/check_size
 	@[ $$(($(subst k,* 1024,$(subst m, * 1024k,$(1))))) -gt "$$(stat -c%s $@)" ] || { \
-		echo "WARNING: Image file $@ is too big"; \
+		echo "WARNING: Image file $@ is too big" >&2; \
 		rm -f $@; \
 	}
 endef