libnetlink: Double the dump buffer size

There have been reports about 'ip addr' printing "Message truncated" on
systems with large numbers of VFs. Although I haven't been able to get
my hands on hardware suitable to reproduce this, increasing the dump
buffer has been reported to resolve the issue. For want of a better
idea, just double the buffer size to 32k.

Feels like this opportunistic buffer size selection is rather
workarounding a design flaw in libnetlink or maybe even the netlink
protocol itself.
Signed-off-by: Phil Sutter <phil@nwl.cc>

lib/libnetlink.c

@@ -223,7 +223,7 @@ int rtnl_dump_filter_l(struct rtnl_handle *rth,
 		.msg_iov = &iov,
 		.msg_iovlen = 1,
 	};
-	char buf[16384];
+	char buf[32768];
 	int dump_intr = 0;
 
 	iov.iov_base = buf;