[fusl] Update fusl

fusl/src/time/clock_gettime.c

 #include <time.h>
 #include <errno.h>
 #include <stdint.h>
 #include "syscall.h"
 #include "libc.h"
 #include "atomic.h"
 
-static int sc_clock_gettime(clockid_t clk, struct timespec *ts)
+#ifdef VDSO_CGT_SYM
+
+void *__vdsosym(const char *, const char *);
+
+static void *volatile vdso_func;
+
+static int cgt_init(clockid_t clk, struct timespec *ts)
 {
-        int r = __syscall(SYS_clock_gettime, clk, ts);
-        if (!r) return r;
+        void *p = __vdsosym(VDSO_CGT_VER, VDSO_CGT_SYM);
+        int (*f)(clockid_t, struct timespec *) =
+                (int (*)(clockid_t, struct timespec *))p;
+        a_cas_p(&vdso_func, (void *)cgt_init, p);
+        return f ? f(clk, ts) : -ENOSYS;
+}
+
+static void *volatile vdso_func = (void *)cgt_init;
+
+#endif
+
+int __clock_gettime(clockid_t clk, struct timespec *ts)
+{
+        int r;
+
+#ifdef VDSO_CGT_SYM
+        int (*f)(clockid_t, struct timespec *) =
+                (int (*)(clockid_t, struct timespec *))vdso_func;
+        if (f) {
+                r = f(clk, ts);
+                if (!r) return r;
+                if (r == -EINVAL) return __syscall_ret(r);
+                /* Fall through on errors other than EINVAL. Some buggy
+                 * vdso implementations return ENOSYS for clocks they
+                 * can't handle, rather than making the syscall. This
+                 * also handles the case where cgt_init fails to find
+                 * a vdso function to use. */
+        }
+#endif
+
+        r = __syscall(SYS_clock_gettime, clk, ts);
         if (r == -ENOSYS) {
                 if (clk == CLOCK_REALTIME) {
                         __syscall(SYS_gettimeofday, ts, 0);
                         ts->tv_nsec = (int)ts->tv_nsec * 1000;
                         return 0;
                 }
                 r = -EINVAL;
         }
-        errno = -r;
-        return -1;
-}
-
-void *__vdsosym(const char *, const char *);
-
-int __clock_gettime(clockid_t clk, struct timespec *ts)
-{
-#ifdef VDSO_CGT_SYM
-        static int (*volatile cgt)(clockid_t, struct timespec *);
-        if (!cgt) {
-                void *f = __vdsosym(VDSO_CGT_VER, VDSO_CGT_SYM);
-                if (!f) f = (void *)sc_clock_gettime;
-                a_cas_p(&cgt, 0, f);
-        }
-        return cgt(clk, ts);
-#else
-        return sc_clock_gettime(clk, ts);
-#endif
+        return __syscall_ret(r);
 }
 
 weak_alias(__clock_gettime, clock_gettime);