gitlab-ci: only build the default (=latest) and oldest llvm versions

Signed-off-by: Eric Engestrom <eric.engestrom@intel.com>
Reviewed-by: Lionel Landwerlin <lionel.g.landwerlin@intel.com>
Reviewed-by: Eric Anholt <eric@anholt.net>

.gitlab-ci.yml

     GALLIUM_DRIVERS: "i915,iris,nouveau,kmsro,r300,r600,freedreno,svga,swrast,v3d,vc4,virgl,etnaviv"
     LLVM_VERSION: "5.0"
 
-meson-gallium-clover-llvm5:
+meson-gallium-clover-llvm:
   extends: .meson-build
   variables:
     UNWIND: "true"
       -D gallium-xa=false
       -D gallium-nine=false
       -D gallium-opencl=icd
-    GALLIUM_DRIVERS: "r600"
-    LLVM_VERSION: "5.0"
-
-meson-gallium-clover-llvm6:
-  extends: meson-gallium-clover-llvm5
-  variables:
-    LLVM_VERSION: "6.0"
+    GALLIUM_DRIVERS: "r600,radeonsi"
 
-meson-gallium-clover-llvm7:
-  extends: meson-gallium-clover-llvm5
+meson-gallium-clover-llvm39:
+  extends: meson-gallium-clover-llvm
   variables:
-    GALLIUM_DRIVERS: "r600,radeonsi"
-    LLVM_VERSION: "7"
+    GALLIUM_DRIVERS: "r600"
+    LLVM_VERSION: "3.9"
 
 meson-gallium-st-other:
   extends: .meson-build
     LLVM_VERSION: "3.9"
     GALLIUM_DRIVERS: "i915,nouveau,kmsro,r300,r600,freedreno,svga,swrast,v3d,vc4,virgl,etnaviv"
 
-make-gallium-st-clover-llvm-39:
+make-gallium-st-clover-llvm:
   extends: .make-build
   variables:
     MAKE_CHECK_COMMAND: "true"
-    LLVM_VERSION: "3.9"
     DRI_LOADERS: >
       --disable-glx
       --disable-gbm
       --disable-va
       --disable-omx-bellagio
       --disable-gallium-osmesa
-    GALLIUM_DRIVERS: "r600"
     LIBUNWIND_FLAGS: --enable-libunwind
+    GALLIUM_DRIVERS: "r600,radeonsi"
 
-make-gallium-st-clover-llvm-4:
-  extends: make-gallium-st-clover-llvm-39
-  variables:
-    LLVM_VERSION: "4.0"
-
-make-gallium-st-clover-llvm-5:
-  extends: make-gallium-st-clover-llvm-39
-  variables:
-    LLVM_VERSION: "5.0"
-
-make-gallium-st-clover-llvm-6:
-  extends: make-gallium-st-clover-llvm-39
-  variables:
-    LLVM_VERSION: "6.0"
-
-make-gallium-st-clover-llvm-7:
-  extends: make-gallium-st-clover-llvm-39
+make-gallium-st-clover-llvm-39:
+  extends: make-gallium-st-clover-llvm
   variables:
-    LLVM_VERSION: "7"
-    GALLIUM_DRIVERS: "r600,radeonsi"
+    LLVM_VERSION: "3.9"
+    GALLIUM_DRIVERS: "r600"
 
 make-gallium-st-other:
   extends: .make-build

.gitlab-ci/Dockerfile.ubuntu

       libva-dev \
       llvm-3.9-dev \
       libclang-3.9-dev \
-      llvm-4.0-dev \
-      libclang-4.0-dev \
       llvm-5.0-dev \
       llvm-6.0-dev \
       llvm-7-dev \