Revert "utils/brmake: add option to run in docker"

All our documented uses of utils/docker-run, besides running it
standalone to get an interactive shell, is to use it as a prefix
to the otherwise standard command to run, e.g.:
  - ./utils/docker-run make foo_defconfig
  - ./utils/docker-run make menuconfig
  - ./utils/docker-run make
  - ./utils/docker-run make check-package

Commit 8aad67f157 (utils/brmake: add option to run in docker) departed
from that usual convention, by hiding the call to docker-run inside
brmake, conditioned by an environment variable. The only reason is that
brmake internally used ubuffer. This is no longer the case, so we can
now use brmake together with docker-run in the usual manner.

This basically reverts commit 8aad67f157,
after resolving the conflict due to the removal of unbuffer in te
previous commit.

Signed-off-by: Yann E. MORIN <yann.morin.1998@free.fr>
Cc: Arnout Vandecappelle (Essensium/Mind) <arnout@mind.be>
Signed-off-by: Arnout Vandecappelle <arnout@mind.be>

utils/brmake

@@ -7,13 +7,7 @@ main() {
 
     start=${SECONDS}
 
-    if [ -n "$BR2_DOCKER" ]; then
-        docker=("${0%/*}/docker-run")
-    else
-        docker=()
-    fi
-
-    ( exec 2>&1; "${docker[@]}" make "${@}"; ) \
+    ( exec 2>&1; make "${@}" ) \
     > >( while read -r line; do
              printf "%(%Y-%m-%dT%H:%M:%S)T %s\n" -1 "${line}"
          done \

utils/readme.txt

@@ -7,9 +7,6 @@ brmake
     front of each line, redirects all of the build output to a file
     ("'br.log' in the current directory), and just outputs the Buildroot
     messages (those lines starting with >>>) on stdout.
-    To run this within a container using docker-run (see below), set
-    BR2_DOCKER=y in the environment, i.e. call it as
-    `BR2_DOCKER=y utils/brmake`.
     Do not run this script for interactive configuration (e.g. menuconfig)
     or on an unconfigured directory. The output is redirected so you will see
     nothing.