package/smcroute: don't override dependencies

Don't override SMCROUTE_DEPENDENCIES in a conditional

Signed-off-by: Fabrice Fontaine <fontaine.fabrice@gmail.com>
Signed-off-by: Arnout Vandecappelle (Essensium/Mind) <arnout@mind.be>

package/smcroute/smcroute.mk

@@ -13,7 +13,7 @@ SMCROUTE_CPE_ID_VENDOR = troglobit
 SMCROUTE_CONF_OPTS = --enable-mrdisc
 
 ifeq ($(BR2_PACKAGE_LIBCAP),y)
-SMCROUTE_DEPENDENCIES = libcap
+SMCROUTE_DEPENDENCIES += libcap
 SMCROUTE_CONF_OPTS += --with-libcap
 else
 SMCROUTE_CONF_OPTS += --without-libcap