gitlab-ci: add a new job that builds a base test image for VK

Signed-off-by: Samuel Pitoiset <samuel.pitoiset@gmail.com>
Reviewed-by: Michel Dänzer <mdaenzer@redhat.com>
diff --git a/.gitlab-ci.yml b/.gitlab-ci.yml
index 9aea544..70a440c 100644
--- a/.gitlab-ci.yml
+++ b/.gitlab-ci.yml
@@ -111,6 +111,12 @@
   variables:
     DEBIAN_TAG: &x86_test-gl "2019-12-05"
 
+# Debian 10 based x86 test image for VK
+x86_test-vk:
+  extends: x86_build
+  variables:
+    DEBIAN_TAG: &x86_test-vk "2019-11-22"
+
 # Debian 9 based x86 build image (old LLVM)
 x86_build_old:
   extends: x86_build