timerfd: Expect periodic timer performance failures

The current timerfd implementation fails to correctly count events on a
nanosecond callout interval. The timerfd__periodic_timer_performance
test detects this and reports failure.

Mark this test as an expected failure so it isn't flagged by CI. A link
to the bug report is attached to the test for reference.

While we're here, clean up some minor style and Make issues.

Fixes:		834c1ba793 ("timerfd: Add tests")
MFC after:	1 week

tests/sys/kern/Makefile

@@ -54,7 +54,6 @@ PLAIN_TESTS_C+=	subr_unit_test
 ATF_TESTS_C+=	sysctl_kern_proc
 ATF_TESTS_C+=	sys_getrandom
 ATF_TESTS_C+=	timerfd
-CFLAGS.timerfd+=	-I${.CURDIR}
 LIBADD.timerfd+=	pthread
 ATF_TESTS_C+=	tty_pts
 ATF_TESTS_C+=	unix_dgram

tests/sys/kern/timerfd.c

@@ -25,11 +25,11 @@
 #include <atf-c.h>
 
 #include <sys/types.h>
-
 #include <sys/event.h>
 #include <sys/param.h>
 #include <sys/select.h>
 #include <sys/time.h>
+#include <sys/timerfd.h>
 
 #include <errno.h>
 #include <signal.h>
@@ -44,8 +44,6 @@
 #include <time.h>
 #include <unistd.h>
 
-#include <sys/timerfd.h>
-
 /* Time in ns that sleeps are allowed to take longer for in unit tests. */
 #define TIMER_SLACK (90000000)
 
@@ -739,6 +737,7 @@ ATF_TC_BODY(timerfd__periodic_timer_performance, tc)
 	uint64_t timeouts;
 	ATF_REQUIRE(read(timerfd, &timeouts, sizeof(timeouts)) ==
 	    (ssize_t)sizeof(timeouts));
+	atf_tc_expect_fail("https://bugs.freebsd.org/bugzilla/show_bug.cgi?id=294053");
 	ATF_REQUIRE_MSG(timeouts >= 400000000, "%ld", (long)timeouts);
 
 	ATF_REQUIRE(close(timerfd) == 0);