travis: enable compilation for ppc64le

qemu-static from ubuntu/xenial contains a required fix
and now we can execute compilation for ppc64le in travis.

v2: rebase on criu-dev
v3: set QEMU_CPU=POWER8 to avoid segfaults of qemu-ppc64le-static

> > By default, both qemu and gcc5 produce code on ppc64el which will run on
> > POWER7 platform.  However, in debian gcc build instruction, gcc is explicitly
> > built to produce code for POWER8 platform, which, obviously has additional
> > instructions.

v4: use ubuntu:trusty. xenial and wily has a bug:
Processing triggers for libc-bin (2.21-0ubuntu4.1) ...
/sbin/ldconfig.real: 5: /sbin/ldconfig.real: Syntax error: ")" unexpected
/sbin/ldconfig.real: 5: /sbin/ldconfig.real: Syntax error: ")" unexpected

v5: arm, x86, aarch64 were removed by mistake
Signed-off-by: Andrew Vagin <avagin@virtuozzo.com>
Signed-off-by: Pavel Emelyanov <xemul@virtuozzo.com>

.travis.yml

@@ -7,6 +7,7 @@ env:
   - TR_ARCH=x86_64
   - TR_ARCH=armv7hf
   - TR_ARCH=aarch64
+  - TR_ARCH=ppc64le
 script:
   - sudo make -C scripts/build $TR_ARCH
   - sudo ./scripts/travis-tests $TR_ARCH

scripts/build/Dockerfile.ppc64le.hdr

-FROM ppc64le/ubuntu
+FROM ppc64le/ubuntu:trusty
 
+ENV QEMU_CPU POWER8
 COPY scripts/build/qemu-user-static/usr/bin/qemu-ppc64le-static /usr/bin/qemu-ppc64le-static

scripts/build/Dockerfile.tmpl

+RUN apt-get clean
+
 RUN apt-get update
 
-RUN apt-get update && apt-get install -y \
+RUN apt-get install -y \
                 build-essential \
                 protobuf-c-compiler \
                 libprotobuf-c0-dev \

scripts/build/extract-deb-pkg

@@ -3,8 +3,8 @@ set -e
 test -d $1 && exit
 mkdir $1
 cd $1
-pkg=`curl http://mirror.yandex.ru/debian/dists/jessie/main/binary-amd64/Packages.gz | zcat | grep "Filename.*$1" | awk '{ print $2 }'`
-wget "http://mirror.yandex.ru/debian/$pkg"
+pkg=`curl http://mirror.yandex.ru/ubuntu/ubuntu/dists/xenial/universe/binary-amd64/Packages.gz | zcat | grep "Filename.*$1" | awk '{ print $2 }'`
+wget "http://mirror.yandex.ru/ubuntu/$pkg"
 pkg=`basename $pkg`
 ar vx $pkg
 tar -xJvf data.tar.xz