fusefs: suppress some Coverity resource leak CIDs in the tests

The fusefs tests deliberately leak file descriptors.  To do otherwise would
add extra complications to the tests' mock FUSE server.  This annotation
should hopefully convince Coverity to shut up about the leaks.

Reviewed by:	uqs
MFC after:	4 days
Sponsored by:	The FreeBSD Foundation

tests/sys/fs/fusefs/utils.hh

@@ -231,6 +231,7 @@ class FuseTest : public ::testing::Test {
 	 * to document the leakage, and provide a single point of suppression
 	 * for static analyzers.
 	 */
+	/* coverity[+close: arg-0] */
 	static void leak(int fd __unused) {}
 
 	/*