[PATCH] nest/config.Y: fix build without babel, bgp, ospf, radv, rip or static

[Fabrice Fontaine]

Build without babel, bgp, ospf, radv, rip or static fails on:

bison  -Dparse.lac=full -Dparse.error=verbose -dv -pcf_ -b
obj/conf/cf-parse obj/conf/cf-parse.y
nest/config.Y:381.20-23: error: symbol LINK is used, but is not
defined as a token and has no rules
  381 |  | dev_proto CHECK LINK bool ';' { DIRECT_CFG->check_link = $4; }
      |                    ^~~~
make[1]: *** [obj/conf/cf-parse.tab.c] Error 1

This error is raised because of the following commit:
https://gitlab.labs.nic.cz/labs/bird/commit/e90dd656cc9126e1fbcc45fb77a10bf1baa2a1b5

This commit assumes that LINK is defined which is not always the case.
Indeed, it seems that LINK is not defined by BFD, MRT, PERF, PIPE, RPKI

To fix this issue, add CF_KEYWORDS(LINK) in nest/config.py

Fixes:
 - http://autobuild.buildroot.org/results/0b00948eed9bb8405b70f3f9112ecce99b365f35

Signed-off-by: Fabrice Fontaine <fontaine.fabrice at gmail.com>
---
 nest/config.Y | 1 +
 1 file changed, 1 insertion(+)

diff --git a/nest/config.Y b/nest/config.Y
index c62501a3..44f392dd 100644
--- a/nest/config.Y
+++ b/nest/config.Y
@@ -75,6 +75,7 @@ CF_KEYWORDS(BGP, PASSWORDS, DESCRIPTION, SORTED)
 CF_KEYWORDS(RELOAD, IN, OUT, MRTDUMP, MESSAGES, RESTRICT, MEMORY, IGP_METRIC, CLASS, DSCP)
 CF_KEYWORDS(TIMEFORMAT, ISO, SHORT, LONG, ROUTE, PROTOCOL, BASE, LOG, S, MS, US)
 CF_KEYWORDS(GRACEFUL, RESTART, WAIT, MAX, FLUSH, AS)
+CF_KEYWORDS(LINK)
 
 /* For r_args_channel */
 CF_KEYWORDS(IPV4, IPV4_MC, IPV4_MPLS, IPV6, IPV6_MC, IPV6_MPLS, IPV6_SADR, VPN4, VPN4_MC, VPN4_MPLS, VPN6, VPN6_MC, VPN6_MPLS, ROA4, ROA6, FLOW4, FLOW6, MPLS, PRI, SEC)
-- 
2.23.0