test: suppress not-found errors for selinuxenabled

if the binary is not available.

test/TEST-13-NSPAWN-SMOKE/test.sh

@@ -17,7 +17,7 @@ test_append_files() {
         busybox="$(type -P busybox-static || type -P busybox)"
         inst_simple "$busybox" "$(dirname "$busybox")/busybox"
 
-        if selinuxenabled >/dev/null; then
+        if command -v selinuxenabled >/dev/null && selinuxenabled; then
             image_install selinuxenabled
             cp -ar /etc/selinux "$workspace/etc/selinux"
         fi

test/units/testsuite-13.sh

@@ -112,7 +112,7 @@ EOF
 }
 
 function check_selinux {
-    if ! selinuxenabled; then
+    if ! command -v selinuxenabled >/dev/null || ! selinuxenabled; then
         echo >&2 "SELinux is not enabled, skipping SELinux-related tests"
         return 0
     fi