[Buildroot] [PATCH v2 5/7] support/dockerfile: install flake8

[Ricardo Martincoski <ricardo.martincoski@gmail.com>]

Use the latest version of the tool because it is actively maintained.
But use a fixed version of the tool and its dependencies to get stable
results. It can be manually bumped from time to time.

Signed-off-by: Ricardo Martincoski <ricardo.martincoski@gmail.com>
Cc: Arnout Vandecappelle <arnout@mind.be>
Cc: Peter Korsgaard <peter@korsgaard.com>
Cc: Thomas Petazzoni <thomas.petazzoni@bootlin.com>
Cc: Yann E. MORIN <yann.morin.1998@free.fr>
---
Changes v1 -> v2:  (suggested by Yann E. MORIN)
  - install flake8 to the base docker image instead of adding sudo to
    install tools on the fly.
---
 support/docker/Dockerfile | 7 ++++++-
 1 file changed, 6 insertions(+), 1 deletion(-)

diff --git a/support/docker/Dockerfile b/support/docker/Dockerfile
index ce3fdd9..f2ba064 100644
--- a/support/docker/Dockerfile
+++ b/support/docker/Dockerfile
@@ -27,10 +27,15 @@ RUN dpkg --add-architecture i386 && \
         cvs bzr git mercurial subversion wget \
         cpio unzip \
         libncurses5-dev \
-        python-nose2 python-pexpect qemu-system-arm qemu-system-x86 && \
+        python-nose2 python-pexpect qemu-system-arm qemu-system-x86 \
+        python-pip && \
     apt-get -y autoremove && \
     apt-get -y clean
 
+# For check-flake8
+RUN pip install -q setuptools
+RUN pip install -q flake8==3.5.0 mccabe==0.6.1 pycodestyle==2.3.1 pyflakes==1.6.0
+
 # To be able to generate a toolchain with locales, enable one UTF-8 locale
 RUN sed -i 's/# \(en_US.UTF-8\)/\1/' /etc/locale.gen && \
     /usr/sbin/locale-gen
-- 
2.7.4