unix: update Linux to v4.13 kernel and v2.26 glibc

This change updates the Linux symbols to correspond to v4.13 of the
kernel and v2.26 of glibc. To get everything building correctly, newer
versions of the build tools are required. Instead of trying to get an
Ubuntu 17.10 docker image working, we just add Artful sources to
/etc/apt/sources.list to get a similar effect.

Now that the kernel UAPI is updated, FS_MAX_KEY_SIZE and fscrypt_key no
longer need to be manually declared, as they are now in the proper
kernel headers.

Change-Id: I5f14c99fd70b43dbb8b44e05f53e4e9f09c9a345
Reviewed-on: https://go-review.googlesource.com/61771
Reviewed-by: Ian Lance Taylor <iant@golang.org>

unix/linux/Dockerfile

@@ -1,5 +1,8 @@
 FROM ubuntu:16.04
 
+# Use the most recent ubuntu sources
+RUN echo 'deb http://en.archive.ubuntu.com/ubuntu/ artful main universe' >> /etc/apt/sources.list
+
 # Dependencies to get the git sources and go binaries
 RUN apt-get update && apt-get install -y \
         curl \
@@ -9,10 +12,10 @@ RUN apt-get update && apt-get install -y \
 # Get the git sources. If not cached, this takes O(5 minutes).
 WORKDIR /git
 RUN git config --global advice.detachedHead false
-# Linux Kernel: Released 19 Feb 2017
-RUN git clone --branch v4.10 --depth 1 https://kernel.googlesource.com/pub/scm/linux/kernel/git/torvalds/linux
-# GNU C library: Released 05 Feb 2017 (we should try to get a secure way to clone this)
-RUN git clone --branch glibc-2.25 --depth 1 git://sourceware.org/git/glibc.git
+# Linux Kernel: Released 03 Sep 2017
+RUN git clone --branch v4.13 --depth 1 https://kernel.googlesource.com/pub/scm/linux/kernel/git/torvalds/linux
+# GNU C library: Released 02 Aug 2017 (we should try to get a secure way to clone this)
+RUN git clone --branch glibc-2.26 --depth 1 git://sourceware.org/git/glibc.git
 
 # Get Go 1.8 (https://github.com/docker-library/golang/blob/master/1.8/Dockerfile)
 ENV GOLANG_VERSION 1.8

unix/linux/types.go

@@ -114,14 +114,6 @@ struct stat {
 
 #endif
 
-// Certain constants and structs are missing from the fs/crypto UAPI
-#define FS_MAX_KEY_SIZE                 64
-struct fscrypt_key {
-  __u32 mode;
-  __u8 raw[FS_MAX_KEY_SIZE];
-  __u32 size;
-};
-
 #ifdef TCSETS2
 // On systems that have "struct termios2" use this as type Termios.
 typedef struct termios2 termios_t;