gitlab-ci: Move LLVM/clang 6/7 packages to the x86_build_old image

They're available in Debian 9 (stretch) as well.

This will avoid conflicts with packages from Debian testing.

Reviewed-by: Erik Faye-Lund <erik.faye-lund@collabora.com>
Reviewed-by: Eric Anholt <eric@anholt.net>
Part-of: <https://gitlab.freedesktop.org/mesa/mesa/-/merge_requests/5296>
diff --git a/.gitlab-ci.yml b/.gitlab-ci.yml
index 2e4290d..a2343ed 100644
--- a/.gitlab-ci.yml
+++ b/.gitlab-ci.yml
@@ -137,7 +137,7 @@
     - .fdo.container-build@debian
     - .container
   variables:
-    FDO_DISTRIBUTION_TAG: &x86_build "2020-05-19"
+    FDO_DISTRIBUTION_TAG: &x86_build "2020-05-29"
 
 .use-x86_build:
   variables:
@@ -179,7 +179,7 @@
 x86_build_old:
   extends: x86_build
   variables:
-    FDO_DISTRIBUTION_TAG: &x86_build_old "2020-04-27"
+    FDO_DISTRIBUTION_TAG: &x86_build_old "2020-06-02"
     FDO_DISTRIBUTION_VERSION: stretch-slim
 
 .use-x86_build_old:
@@ -483,6 +483,7 @@
       -D glx=disabled
       -D egl=disabled
       -D gbm=disabled
+    GALLIUM_DRIVERS: "r600,radeonsi"
     GALLIUM_ST: >
       -D dri3=disabled
       -D gallium-vdpau=disabled
@@ -493,12 +494,8 @@
       -D gallium-nine=false
       -D gallium-opencl=icd
   script:
-    - export GALLIUM_DRIVERS="r600,radeonsi"
     - .gitlab-ci/meson-build.sh
     - LLVM_VERSION=8 .gitlab-ci/meson-build.sh
-    - export GALLIUM_DRIVERS="i915,r600"
-    - LLVM_VERSION=6.0 .gitlab-ci/meson-build.sh
-    - LLVM_VERSION=7 .gitlab-ci/meson-build.sh
 
 meson-clover-old-llvm:
   extends:
@@ -516,6 +513,8 @@
     - LLVM_VERSION=3.9 .gitlab-ci/meson-build.sh
     - LLVM_VERSION=4.0 .gitlab-ci/meson-build.sh
     - LLVM_VERSION=5.0 .gitlab-ci/meson-build.sh
+    - LLVM_VERSION=6.0 .gitlab-ci/meson-build.sh
+    - LLVM_VERSION=7 .gitlab-ci/meson-build.sh
 
 meson-vulkan:
   extends: .meson-build