Add GitLab CI configuration

Builds the driver against all supported versions of xserver, with both
gcc and clang for xserver >= 1.18 (older versions cause warnings with
clang). Compiler warnings are treated as errors.

The xserver 1.15 build uses standalone glamor, the xserver 1.13 & 1.14
builds use --disable-glamor.

With the latest xserver version, make install and make distcheck are
tested as well.

.gitlab-ci.yml

@@ -0,0 +1,79 @@
+image: registry.freedesktop.org/xorg/driver/xf86-video-amdgpu:debian-testing-20181003
+
+stages:
+  - build
+
+# The default build instructions
+.default_build:
+  stage: build
+  script:
+  - ./autogen.sh
+  - make -j$(nproc) check V=1
+  variables:
+    CFLAGS: "-pipe -g -O2 -Werror"
+    ACLOCAL_PATH: /usr/local/xserver-$XSERVER_VERSION/share/aclocal
+    PKG_CONFIG_PATH: /usr/local/xserver-$XSERVER_VERSION/lib/pkgconfig
+
+xserver-1.20:
+  extends: .default_build
+  script:
+  - ./autogen.sh
+  - make -j$(nproc) check V=1
+  - make install V=1
+  - make -j$(nproc) distcheck
+  variables:
+    XSERVER_VERSION: "1.20"
+
+xserver-1.20-clang:
+  extends: .default_build
+  variables:
+    CC: clang
+    XSERVER_VERSION: "1.20"
+
+xserver-1.13:
+  extends: .default_build
+  script:
+  - ./autogen.sh --disable-glamor
+  - make -j$(nproc) check V=1
+  variables:
+    XSERVER_VERSION: "1.13"
+
+xserver-1.14:
+  extends: xserver-1.13
+  variables:
+    XSERVER_VERSION: "1.14"
+
+xserver-1.15:
+  extends: .default_build
+  variables:
+    XSERVER_VERSION: "1.15"
+
+xserver-1.16:
+  extends: .default_build
+  variables:
+    XSERVER_VERSION: "1.16"
+
+xserver-1.17:
+  extends: .default_build
+  variables:
+    XSERVER_VERSION: "1.17"
+
+xserver-1.18:
+  extends: .default_build
+  variables:
+    XSERVER_VERSION: "1.18"
+
+xserver-1.18-clang:
+  extends: xserver-1.18
+  variables:
+    CC: clang
+
+xserver-1.19:
+  extends: .default_build
+  variables:
+    XSERVER_VERSION: "1.19"
+
+xserver-1.19-clang:
+  extends: xserver-1.19
+  variables:
+    CC: clang