virkmodtest: Don't fail if modprobe doesn't exist

On some very basic installations (e.g. some container images) the
modprobe binary might be missing. If that is the case, don't fail
virkmodtest.
Signed-off-by: NMichal Privoznik <mprivozn@redhat.com>
Reviewed-by: NDaniel P. Berrangé <berrange@redhat.com>

tests/virkmodtest.c

@@ -46,7 +46,12 @@ testKModConfig(const void *args ATTRIBUTE_UNUSED)
      */
     outbuf = virKModConfig();
     if (!outbuf) {
-        fprintf(stderr, "Failed to get config\n");
+        if (virFileIsExecutable(MODPROBE)) {
+            fprintf(stderr, "Failed to get config\n");
+        } else {
+            /* modprobe doesn't exist, do not claim error. */
+            ret = 0;
+        }
         goto cleanup;
     }
     ret = 0;