[gnome-build-meta/barthalion/x86_64-local-cache] Use Docker volume for caching sources on x86_64 runner

[Bartłomiej Piotrowski <bpiotrowski src gnome org>]

commit 3ca6bfc34c1752d918621fe2746b7031b2ea598b
Author: Bartłomiej Piotrowski <bpiotrowski gnome org>
Date:   Wed Jul 29 22:36:54 2020 +0200

    Use Docker volume for caching sources on x86_64 runner

 .gitlab-ci.yml | 9 +++++++--
 1 file changed, 7 insertions(+), 2 deletions(-)
---
diff --git a/.gitlab-ci.yml b/.gitlab-ci.yml
index 133fe827..e7a417ab 100644
--- a/.gitlab-ci.yml
+++ b/.gitlab-ci.yml
@@ -51,6 +51,10 @@ default:
           push: true
     EOF
 
+    if [ $ARCH == 'x86_64' ]; then
+        echo "sourcedir: /cache/buildstream/sources" >> build.conf
+    fi
+
   - |
     case "$FLATPAK_BRANCH" in
       master)
@@ -128,7 +132,6 @@ default:
   - if: $CI_MERGE_REQUEST_ID == null
     when: manual
     allow_failure: true
-  cache: *bst-cache
   artifacts:
     when: always
     paths:
@@ -220,6 +223,7 @@ default:
   - gnome-build-meta
   variables:
     ARCH: aarch64
+  cache: *bst-cache
 
 .arm: &arm
   image: "${DOCKER_AARCH64}"
@@ -228,6 +232,7 @@ default:
   - gnome-build-meta
   variables:
     ARCH: arm
+  cache: *bst-cache
 
 .ppc64le: &ppc64le
   image: "${DOCKER_PPC64LE}"
@@ -237,6 +242,7 @@ default:
   variables:
     ARCH: ppc64le
   allow_failure: true
+  cache: *bst-cache
 
 #
 # "Real" CI jobs
@@ -253,7 +259,6 @@ track:
   # only run on branches targeting master
   rules:
   - if: $FLATPAK_BRANCH == 'master' && $CI_MERGE_REQUEST_ID == null
-  cache: *bst-cache
   artifacts:
     paths:
     - project.refs