util/u_thread: don't restrict u_thread_get_time_nano() to __linux__

pthread_getcpuclockid() and clock_gettime() are also available on at least
OpenBSD, FreeBSD, NetBSD, DragonFly, Cygwin.
Signed-off-by: Jonathan Gray <jsg@jsg.id.au>
Signed-off-by: Marek Olšák <marek.olsak@amd.com>

src/util/u_thread.h

@@ -149,7 +149,7 @@ util_get_L3_for_pinned_thread(thrd_t thread, unsigned cores_per_L3)
 static inline int64_t
 u_thread_get_time_nano(thrd_t thread)
 {
-#if defined(__linux__) && defined(HAVE_PTHREAD)
+#if defined(HAVE_PTHREAD)
    struct timespec ts;
    clockid_t cid;