gitlab-ci: Add CI/CD configuration

Signed-off-by: Enric Balletbo i Serra <enric.balletbo@collabora.com>

.gitlab-ci/fragment.cfg

+# CONFIG_LOCALVERSION_AUTO is not set
+CONFIG_SERIAL_8250_DW=y
+CONFIG_X86_AMD_PLATFORM_DEVICE=y
+CONFIG_MFD_INTEL_LPSS_PCI=y
+CONFIG_USB_GADGET=y
+CONFIG_USB_ETH=y
+CONFIG_USB_RTL8152=y

.gitlab-ci/gitlab-ci.yml

+variables:
+  APT_OPTIONS: -y --allow-unauthenticated
+  CCACHE_BASEDIR: $CI_PROJECT_DIR
+  CCACHE_DIR: $CI_PROJECT_DIR/ccache
+
+stages:
+  - build
+
+# Retry jobs after runner system failures
+.retry: &retry
+  retry:
+    max: 2
+    when:
+      - runner_system_failure
+
+build:
+  stage: build
+  image: debian:testing
+  cache:                                                             
+    paths:                                                                                                 
+      - ccache
+  before_script:
+    - echo "deb  http://deb.debian.org/debian testing main contrib non-free" > /etc/apt/sources.list
+    - echo "deb-src http://deb.debian.org/debian testing main contrib non-free" >> /etc/apt/sources.list
+    - apt-get update && apt-get $APT_OPTIONS build-dep linux && apt-get $APT_OPTIONS install devscripts ccache fakeroot build-essential
+  script:
+    - export PATH="/usr/lib/ccache:$PATH"
+    - ccache -s
+    - scripts/kconfig/merge_config.sh -m arch/x86/configs/x86_64_defconfig .gitlab-ci/fragment.cfg
+    - make olddefconfig
+    - make -j$(nproc)
+    - make INSTALL_MOD_PATH=./tmp modules_install
+    - cd tmp
+    - tar -cJf ../modules.tar.xz .
+    - cd - > /dev/null
+    - mkdir artifacts
+    - cp arch/x86/boot/bzImage artifacts/
+    - cp modules.tar.xz artifacts/
+  artifacts:
+    name: binaries
+    paths:
+      - $CI_PROJECT_DIR/artifacts/*
+