platform_compat: guard linux/netlink.h and nl function with __linux__ (FreeBSD)

lib/platform_compat.c

@@ -24,8 +24,10 @@
     #include <arpa/inet.h>
     #include <ifaddrs.h>
     #include <net/if.h>
+    #ifdef __linux__
     #include <linux/netlink.h>
     #include <linux/rtnetlink.h>
+    #endif
     #ifndef IFA_F_TEMPORARY
     #define IFA_F_TEMPORARY 0x01
     #endif
@@ -114,6 +116,7 @@ int get_interface_ipv6_by_index(uint32_t netif_index, int temporary, uint8_t* ad
     return found ? 0 : -1;
 }
 
+#ifdef __linux__
 /* get_interface_ipv6_addr_nl — netlink-based IPv6 address lookup with proper IFA_F_* flags
  *
  * getifaddrs() ifa_flags contains interface flags (IFF_UP etc.), NOT address flags
@@ -194,6 +197,13 @@ int get_interface_ipv6_addr_nl(uint32_t netif_index, int prefer_stable, uint8_t*
     if (has_fallback) { memcpy(addr_out, fallback, 16); return 0; }
     return -1;
 }
+#else
+int get_interface_ipv6_addr_nl(uint32_t netif_index, int prefer_stable, uint8_t* addr_out) {
+    (void)netif_index; (void)prefer_stable;
+    if (addr_out) memset(addr_out, 0, 16);
+    return -1;
+}
+#endif
 
 uint32_t get_default_route_netif_index(int family) {
     if (family != AF_INET && family != AF_INET6) return 0;