unix: update Dockerfile to Linux 5.7 and Go 1.14.4

Some BPF related macros were converted to enum values, so add them to
linux/types.go

Change-Id: I6fa9cc17b6ff3be91f3aa0b7ef2cfe19faf069bd
Reviewed-on: https://go-review.googlesource.com/c/sys/+/236097
Run-TryBot: Tobias Klauser <tobias.klauser@gmail.com>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: Matt Layher <mdlayher@gmail.com>
diff --git a/unix/zerrors_linux_amd64.go b/unix/zerrors_linux_amd64.go
index 47a57fe..c4bf9cb 100644
--- a/unix/zerrors_linux_amd64.go
+++ b/unix/zerrors_linux_amd64.go
@@ -75,6 +75,7 @@
 	FP_XSTATE_MAGIC2                 = 0x46505845
 	FS_IOC_ENABLE_VERITY             = 0x40806685
 	FS_IOC_GETFLAGS                  = 0x80086601
+	FS_IOC_GET_ENCRYPTION_NONCE      = 0x8010661b
 	FS_IOC_GET_ENCRYPTION_POLICY     = 0x400c6615
 	FS_IOC_GET_ENCRYPTION_PWSALT     = 0x40106614
 	FS_IOC_SET_ENCRYPTION_POLICY     = 0x800c6613