package/lua: don't override dependencies

Don't override LUA_DEPENDENCIES in a conditional

Signed-off-by: Fabrice Fontaine <fontaine.fabrice@gmail.com>
Signed-off-by: Peter Korsgaard <peter@korsgaard.com>
(cherry picked from commit bb0ca7f32eaa3c3535c04e2f84763be75606714c)
Signed-off-by: Peter Korsgaard <peter@korsgaard.com>

package/lua/lua.mk

@@ -40,12 +40,12 @@ LUA_MYLIBS += -ldl
 endif
 
 ifeq ($(BR2_PACKAGE_LUA_READLINE),y)
-LUA_DEPENDENCIES = readline ncurses
+LUA_DEPENDENCIES += readline ncurses
 LUA_MYLIBS += -lreadline -lhistory -lncurses
 LUA_CFLAGS += -DLUA_USE_READLINE
 else
 ifeq ($(BR2_PACKAGE_LUA_LINENOISE),y)
-LUA_DEPENDENCIES = linenoise
+LUA_DEPENDENCIES += linenoise
 LUA_MYLIBS += -llinenoise
 LUA_CFLAGS += -DLUA_USE_LINENOISE
 endif