CI: Specify tmpdir for running golang unit tests

It is possible for the `go-test.sh` script to fail when attemping to
write to a file as it can already be closed. This problem seems to
relate to the golang `testing` package itself so work around the
problem by specifying an explicit temporary directory for `testing` to
create files in.

Fixes #869.

Signed-off-by: James O. D. Hunt <james.o.hunt@intel.com>

.ci/go-test.sh

@@ -10,6 +10,9 @@ set -e
 script_name=${0##*/}
 typeset -A long_options
 
+# directory to use for temporary files
+TMPDIR=${TMPDIR:-/tmp}
+
 long_options=(
 	[help]="Show usage"
 	[list]="List available packages"
@@ -27,7 +30,7 @@ timeout_value=${KATA_GO_TEST_TIMEOUT:-30s}
 [ "$(go env GOARCH)" = "amd64" ] && race="-race"
 
 # KATA_GO_TEST_FLAGS can be set to change the flags passed to "go test".
-go_test_flags=${KATA_GO_TEST_FLAGS:-"-v $race -timeout $timeout_value"}
+go_test_flags=${KATA_GO_TEST_FLAGS:-"-v $race -timeout $timeout_value -outputdir \"${TMPDIR}\""}
 
 # Notes:
 #