migrate to linux-headers

Rather than having a toolchain package we use for the cross-compilers and
installing a different one for the target build dir, use the same package.
This makes updating more logical as we only have to do it in one place.

BUG=chromium-os:24928
TEST=`cbuildbot amd64-generic-full` works
TEST=`cbuildbot arm-generic-full` works
TEST=`cbuildbot x86-generic-full` works
TEST=build_packages+build_image for x86-alex boots & works

Change-Id: Ib083c3d2eae75d6f5437203990599cdc837dd9dc
Reviewed-on: https://gerrit.chromium.org/gerrit/24722
Reviewed-by: Anush Elangovan <anush@google.com>
Commit-Ready: Mike Frysinger <vapier@chromium.org>
Tested-by: Mike Frysinger <vapier@chromium.org>

chroot_version_hooks.d/40_kernel_headers

@@ -0,0 +1,38 @@
+# Copyright (c) 2012 The Chromium OS Authors. All rights reserved.
+# Use of this source code is governed by a BSD-style license that can be
+# found in the LICENSE file.
+
+# Move from chromeos-base/kernel-headers to sys-kernel/linux-headers.
+
+opkg="chromeos-base/kernel-headers"
+npkg="sys-kernel/linux-headers"
+
+export CLEAN_DELAY=0
+
+update() {
+  local root=$1 board=$2 emerge
+
+  if [[ -z ${board} ]]; then
+    board="root"
+    emerge="sudo -E emerge"
+  else
+    emerge="emerge-${board}"
+  fi
+
+  if portageq has_version ${root} ${opkg}; then
+    info "Migrating ${board} from ${opkg} to ${npkg}"
+    ${emerge} -Cq ${opkg}
+  fi
+  if ! portageq has_version ${root} ${npkg}; then
+    ${emerge} -1gq ${npkg}
+  fi
+}
+
+update / &
+
+for board_root in /build/*; do
+  board=${board_root##*/}
+  update ${board_root} ${board} &
+done
+
+wait

setup_board

@@ -582,17 +582,16 @@ else
   # config to make.conf.board.
   print_board_binhost_config | sudo_append $BOARD_ETC/make.conf.board
 
-  #
-  # Emerge the kernel headers into the board build root.
-  #
-  KERNEL_EMERGE_FLAGS="--select --quiet"
+  # Emerge the kernel headers into the board build root.  Use rdeps to
+  # avoid pulling any spurious DEPEND things in that we don't care about.
+  KERNEL_EMERGE_FLAGS="--select --quiet --root-deps=rdeps"
   if [[ "${FLAGS_usepkg}" -eq "${FLAGS_TRUE}" ||
         "${FLAGS_reuse_pkgs_from_local_boards}" -eq "${FLAGS_TRUE}" ]]; then
     KERNEL_EMERGE_FLAGS+=" --getbinpkg --usepkg"
   fi
 
   sudo -E "${EMERGE_WRAPPER}" ${KERNEL_EMERGE_FLAGS} \
-    chromeos-base/kernel-headers
+    sys-kernel/linux-headers
 
   unset KERNEL_EMERGE_FLAGS
 fi