CI: use /tmp for $GOCACHE

Point the compiler's build cache at /tmp.  This generally requires more
memory, but it's faster, and the build cache would be discarded anyway.

Signed-off-by: Nalin Dahyabhai <[email protected]>

.cirrus.yml

@@ -9,6 +9,7 @@ env:
     DEST_BRANCH: "main"
     GOPATH: "/var/tmp/go"
     GOSRC: "${GOPATH}/src/github.com/containers/buildah"
+    GOCACHE: "/tmp/go-build"
     # Overrides default location (/tmp/cirrus) for repo clone
     CIRRUS_WORKING_DIR: "${GOSRC}"
     # Shell used to execute all script commands
@@ -146,7 +147,7 @@ cross_build_task:
     script:
         - go version
         - make -j cross CGO_ENABLED=0
-        - df -hT /tmp
+        - du -sh `go env GOCACHE`
     binary_artifacts:
         path: ./bin/*
 
@@ -169,6 +170,7 @@ unit_task:
     setup_script: '${SCRIPT_BASE}/setup.sh |& ${_TIMESTAMP}'
     build_script: '${SCRIPT_BASE}/build.sh |& ${_TIMESTAMP}'
     unit_test_script: '${SCRIPT_BASE}/test.sh unit |& ${_TIMESTAMP}'
+    du_script: du -sh `go env GOCACHE`
 
     binary_artifacts:
         path: ./bin/*
@@ -193,6 +195,7 @@ conformance_task:
 
     setup_script: '${SCRIPT_BASE}/setup.sh conformance |& ${_TIMESTAMP}'
     conformance_test_script: '${SCRIPT_BASE}/test.sh conformance |& ${_TIMESTAMP}'
+    du_script: du -sh `go env GOCACHE`
 
 
 integration_task:
@@ -237,6 +240,7 @@ integration_task:
     setup_script: '${SCRIPT_BASE}/setup.sh |& ${_TIMESTAMP}'
     build_script: '${SCRIPT_BASE}/build.sh |& ${_TIMESTAMP}'
     integration_test_script: '${SCRIPT_BASE}/test.sh integration |& ${_TIMESTAMP}'
+    du_script: du -sh `go env GOCACHE`
 
     binary_artifacts:
         path: ./bin/*
@@ -283,6 +287,7 @@ integration_rootless_task:
     setup_script: '${SCRIPT_BASE}/setup.sh |& ${_TIMESTAMP}'
     build_script: '${SCRIPT_BASE}/build.sh |& ${_TIMESTAMP}'
     integration_test_script: '${SCRIPT_BASE}/test.sh integration |& ${_TIMESTAMP}'
+    du_script: du -sh `go env GOCACHE`
 
     binary_artifacts:
         path: ./bin/*