unix/linux: update Dockerfile to Kernel 5.15

Change-Id: I032465fbaecd49ffb6048577cd2f3fcb3d8e11d0
Reviewed-on: https://go-review.googlesource.com/c/sys/+/359678
Trust: Tobias Klauser <tobias.klauser@gmail.com>
Run-TryBot: Tobias Klauser <tobias.klauser@gmail.com>
TryBot-Result: Go Bot <gobot@golang.org>
Reviewed-by: Ian Lance Taylor <iant@golang.org>
diff --git a/unix/zerrors_linux_amd64.go b/unix/zerrors_linux_amd64.go
index 7d8d93b..da55638 100644
--- a/unix/zerrors_linux_amd64.go
+++ b/unix/zerrors_linux_amd64.go
@@ -294,6 +294,7 @@
 	SO_BPF_EXTENSIONS                = 0x30
 	SO_BROADCAST                     = 0x6
 	SO_BSDCOMPAT                     = 0xe
+	SO_BUF_LOCK                      = 0x48
 	SO_BUSY_POLL                     = 0x2e
 	SO_BUSY_POLL_BUDGET              = 0x46
 	SO_CNX_ADVICE                    = 0x35