flot: add error handling to for loop

Signed-off-by: Thomas Petazzoni <thomas.petazzoni@free-electrons.com>
Acked-by: "Yann E. MORIN" <yann.morin.1998@free.fr>
Signed-off-by: Peter Korsgaard <peter@korsgaard.com>

package/flot/flot.mk

@@ -27,7 +27,7 @@ FLOT_FILES = jquery.flot $(addprefix jquery.flot.,\
 
 define FLOT_INSTALL_TARGET_CMDS
 	for i in $(FLOT_FILES); do \
-		$(INSTALL) -m 0644 -D $(@D)/$$i.min.js $(TARGET_DIR)/var/www/$$i.js; \
+		$(INSTALL) -m 0644 -D $(@D)/$$i.min.js $(TARGET_DIR)/var/www/$$i.js || exit 1; \
 	done
 endef