The following revision refers to this bug:
  https://chromium.googlesource.com/chromiumos/third_party/kernel/+/5a03528ae6754fee9f8f9fa7031dcf77a804c027

commit 5a03528ae6754fee9f8f9fa7031dcf77a804c027
Author: Guenter Roeck <groeck@chromium.org>
Date: Tue Oct 30 08:04:52 2018

CHROMIUM: Restrict ALT_SYSCALL code to 64 bit builds

0day reports that 32 bit builds (i386) fail.

>> init/init_task.c:65:69: error: initialization from incompatible pointer type [-Werror=incompatible-pointer-types]
     .thread_info = INIT_THREAD_INFO(init_task),
                                                                        ^
init/init_task.c:65:69: note: (near initialization for 'init_task.thread_info.sys_call_table')

Since we don't support 32-bit builds (the syscall API is different), limit
ALT_SYSCALL support to 64-bit builds. Do it using ARCH_HAS_ALT_SYSCALL to make
sure it does not pop up again.

BUG= chromium:899792 
TEST=Build i386:allmodconfig

Change-Id: Ibf5323b15a00ca3a8d27e0f16e225e7e6e278869
Signed-off-by: Guenter Roeck <groeck@chromium.org>
Reviewed-on: https://chromium-review.googlesource.com/1305534
Reviewed-by: Matthias Kaehlcke <mka@chromium.org>

[modify] https://crrev.com/5a03528ae6754fee9f8f9fa7031dcf77a804c027/arch/x86/Kconfig
[modify] https://crrev.com/5a03528ae6754fee9f8f9fa7031dcf77a804c027/security/chromiumos/Kconfig