Nokia RX-51: Add automated test for running RX-51 build in qemu

This patch contains test/nokia_rx51_test.sh script which automatically
download and compile all needed tools in local temporary directory to
generate a simple MTD images for booting Maemo kernel image by U-Boot from
RAM, eMMC and OneNAND. MTD images are then run in virtual n900 machine
provided by qemu-linaro project.

This script does not need any special privileges, so it can be run as
non-root nobody user.

It can be used to check that U-Boot for Nokia N900 is not broken and can be
successfully booted in emulator.

Script is registered to .azure-pipelines.yml, .gitlab-ci.yml and
.travis.yml so it would be automatically run on those CI services.

Signed-off-by: Pali Rohár <pali@kernel.org>

.gitlab-ci.yml

@@ -170,6 +170,14 @@ Run binman, buildman, dtoc, Kconfig and patman testsuites:
       ./tools/patman/patman --test;
       make testconfig
 
+Run tests for Nokia RX-51 (aka N900):
+  tags: [ 'all' ]
+  stage: testsuites
+  script:
+    - ./tools/buildman/buildman --fetch-arch arm;
+      export PATH=~/.buildman-toolchains/gcc-9.2.0-nolibc/arm-linux-gnueabi/bin/:$PATH;
+      test/nokia_rx51_test.sh
+
 # Test sandbox with test.py
 sandbox test.py:
   tags: [ 'all' ]