unix/linux: update Dockerfile to glibc 2.29 and Go 1.12beta2

Drop the manually defined *_XDP constants which were added to glibc.
Install python3 instead of python because glibc's confugure script now
requires at least 3.4.

Change-Id: Ic19ff4d8aa4dbadeb5438e331ccafeafc2cc9925
Reviewed-on: https://go-review.googlesource.com/c/160957
Run-TryBot: Tobias Klauser <tobias.klauser@gmail.com>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: Brad Fitzpatrick <bradfitz@golang.org>
diff --git a/unix/zerrors_linux_mipsle.go b/unix/zerrors_linux_mipsle.go
index aadfad3..7ddd09d 100644
--- a/unix/zerrors_linux_mipsle.go
+++ b/unix/zerrors_linux_mipsle.go
@@ -41,7 +41,7 @@
 	AF_KEY                               = 0xf
 	AF_LLC                               = 0x1a
 	AF_LOCAL                             = 0x1
-	AF_MAX                               = 0x2c
+	AF_MAX                               = 0x2d
 	AF_MPLS                              = 0x1c
 	AF_NETBEUI                           = 0xd
 	AF_NETLINK                           = 0x10
@@ -706,6 +706,7 @@
 	IN_ISDIR                             = 0x40000000
 	IN_LOOPBACKNET                       = 0x7f
 	IN_MASK_ADD                          = 0x20000000
+	IN_MASK_CREATE                       = 0x10000000
 	IN_MODIFY                            = 0x2
 	IN_MOVE                              = 0xc0
 	IN_MOVED_FROM                        = 0x40
@@ -777,6 +778,7 @@
 	IPV6_MINHOPCOUNT                     = 0x49
 	IPV6_MTU                             = 0x18
 	IPV6_MTU_DISCOVER                    = 0x17
+	IPV6_MULTICAST_ALL                   = 0x1d
 	IPV6_MULTICAST_HOPS                  = 0x12
 	IPV6_MULTICAST_IF                    = 0x11
 	IPV6_MULTICAST_LOOP                  = 0x13
@@ -2058,6 +2060,7 @@
 	TCOOFF                               = 0x0
 	TCOON                                = 0x1
 	TCP_CC_INFO                          = 0x1a
+	TCP_CM_INQ                           = 0x24
 	TCP_CONGESTION                       = 0xd
 	TCP_COOKIE_IN_ALWAYS                 = 0x1
 	TCP_COOKIE_MAX                       = 0x10
@@ -2072,6 +2075,7 @@
 	TCP_FASTOPEN_KEY                     = 0x21
 	TCP_FASTOPEN_NO_COOKIE               = 0x22
 	TCP_INFO                             = 0xb
+	TCP_INQ                              = 0x24
 	TCP_KEEPCNT                          = 0x6
 	TCP_KEEPIDLE                         = 0x4
 	TCP_KEEPINTVL                        = 0x5
@@ -2091,6 +2095,9 @@
 	TCP_QUEUE_SEQ                        = 0x15
 	TCP_QUICKACK                         = 0xc
 	TCP_REPAIR                           = 0x13
+	TCP_REPAIR_OFF                       = 0x0
+	TCP_REPAIR_OFF_NO_WP                 = -0x1
+	TCP_REPAIR_ON                        = 0x1
 	TCP_REPAIR_OPTIONS                   = 0x16
 	TCP_REPAIR_QUEUE                     = 0x14
 	TCP_REPAIR_WINDOW                    = 0x1d
@@ -2105,6 +2112,7 @@
 	TCP_ULP                              = 0x1f
 	TCP_USER_TIMEOUT                     = 0x12
 	TCP_WINDOW_CLAMP                     = 0xa
+	TCP_ZEROCOPY_RECEIVE                 = 0x23
 	TCSAFLUSH                            = 0x5410
 	TCSBRK                               = 0x5405
 	TCSBRKP                              = 0x5486