haproxy: fix linking with lua

Use LUA_LIB_NAME to give lua library name otherwise haproxy can't find
it

Fixes:
 - http://autobuild.buildroot.net/results/28b6672188bb0082ac1467d3b45904880e3634f3

Signed-off-by: Fabrice Fontaine <fontaine.fabrice@gmail.com>
Signed-off-by: Peter Korsgaard <peter@korsgaard.com>

package/haproxy/haproxy.mk

@@ -25,7 +25,9 @@ endif
 
 ifeq ($(BR2_PACKAGE_LUA_5_3),y)
 HAPROXY_DEPENDENCIES += lua
-HAPROXY_MAKE_OPTS += USE_LUA=1
+HAPROXY_MAKE_OPTS += \
+	LUA_LIB_NAME=lua \
+	USE_LUA=1
 endif
 
 ifeq ($(BR2_PACKAGE_OPENSSL),y)