Add .gitlab-ci.yml for build testing

This adds compilation testing using meson on the gitlab instance. It
uses a prebuild image built, described in .gitlab-ci/Dockerfile, based
on Fedora 29.

The image is build and published by running:

  cd .gitlab-ci/
  docker build -t registry.gitlab.gnome.org/gnome/mutter/master:v1 .
  docker push registry.gitlab.gnome.org/gnome/mutter/master:v1

Resolves: https://gitlab.gnome.org/GNOME/mutter/merge_requests/132

.gitlab-ci.yml

@@ -0,0 +1,11 @@
+image: registry.gitlab.gnome.org/gnome/mutter/master:v1
+
+stages:
+ - build
+
+build-mutter:
+  stage: build
+  script:
+    - meson . build -Degl_device=true -Dwayland_eglstream=true
+    - ninja -C build
+    - ninja -C build install

.gitlab-ci/Dockerfile

@@ -0,0 +1,11 @@
+FROM fedora:29
+
+RUN dnf -y update && dnf -y upgrade && \
+    dnf install -y 'dnf-command(builddep)' && \
+    dnf builddep -y mutter && \
+
+# Until Fedora catches up with meson build-deps
+    dnf install -y meson xorg-x11-server-Xorg gnome-settings-daemon-devel egl-wayland-devel xorg-x11-server-Xwayland && \
+
+    dnf install -y intltool redhat-rpm-config make && \
+    dnf clean all