CI: build our own spirv tools

This causes a lot of hiccups on the CL tests, but I've got most of
them fixed in another MR in pieces.

This should at least give a much more realistic baseline.

v2: use script in both places

Reviewed-by: Michel Dänzer <mdaenzer@redhat.com>
Part-of: <https://gitlab.freedesktop.org/mesa/mesa/-/merge_requests/7073>
diff --git a/.gitlab-ci.yml b/.gitlab-ci.yml
index ecc5d46..f9a4576 100644
--- a/.gitlab-ci.yml
+++ b/.gitlab-ci.yml
@@ -258,7 +258,7 @@
   extends:
     - .use-x86_build-base
   variables:
-    FDO_DISTRIBUTION_TAG: &x86_build "2020-10-06-clang10-cl3"
+    FDO_DISTRIBUTION_TAG: &x86_build "2020-10-09-spvtools-1"
 
 .use-x86_build:
   variables:
@@ -330,7 +330,7 @@
 x86_test-gl:
   extends: .use-x86_test-base
   variables:
-    FDO_DISTRIBUTION_TAG: &x86_test-gl "2020-10-06-clang10-cl3"
+    FDO_DISTRIBUTION_TAG: &x86_test-gl "2020-10-09-spvtools-1"
 
 # Debian 10 based x86 test image for VK
 x86_test-vk: