unix: add generic netlink types and constants on Linux

Generic netlink is a generalized netlink family which enables a series
of different communication channels to be multiplexed on a single
netlink family.

For more information, please see: https://lwn.net/Articles/208755/.

Fixes golang/go#21682.

Change-Id: I2095150e06471f4a0e1322fba669573aa8f0a9b1
Reviewed-on: https://go-review.googlesource.com/59931
Run-TryBot: Matt Layher <mdlayher@gmail.com>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: Ian Lance Taylor <iant@golang.org>
diff --git a/unix/zerrors_linux_386.go b/unix/zerrors_linux_386.go
index c12bbb9..33ced1a 100644
--- a/unix/zerrors_linux_386.go
+++ b/unix/zerrors_linux_386.go
@@ -507,6 +507,19 @@
 	F_ULOCK                              = 0x0
 	F_UNLCK                              = 0x2
 	F_WRLCK                              = 0x1
+	GENL_ADMIN_PERM                      = 0x1
+	GENL_CMD_CAP_DO                      = 0x2
+	GENL_CMD_CAP_DUMP                    = 0x4
+	GENL_CMD_CAP_HASPOL                  = 0x8
+	GENL_HDRLEN                          = 0x4
+	GENL_ID_CTRL                         = 0x10
+	GENL_ID_PMCRAID                      = 0x12
+	GENL_ID_VFS_DQUOT                    = 0x11
+	GENL_MAX_ID                          = 0x3ff
+	GENL_MIN_ID                          = 0x10
+	GENL_NAMSIZ                          = 0x10
+	GENL_START_ALLOC                     = 0x13
+	GENL_UNS_ADMIN_PERM                  = 0x10
 	GRND_NONBLOCK                        = 0x1
 	GRND_RANDOM                          = 0x2
 	HUPCL                                = 0x400