linux: Use 64-bit time_t syscall on clock_getcputclockid

The syscall __NR_clock_getres_time64 (for 32-bit) or __NR_clock_getres
(for 64-bit) is used as default.  The 32-bit fallback is used iff
__ASSUME_TIME64_SYSCALLS is not defined, which assumes the kernel ABI
provides either __NR_rt_sigtimedwait (32-bit time_t).

Since the symbol does not use any type which might be affected by the
time_t, there is no need to add a 64-bit variant.

Checked on x86_64-linux-gnu and i686-linux-gnu (on 5.4 and on 4.15
kernel).

Reviewed-by: Alistair Francis <alistair.francis@wdc.com>

sysdeps/unix/sysv/linux/clock_getcpuclockid.c

@@ -30,20 +30,25 @@ __clock_getcpuclockid (pid_t pid, clockid_t *clock_id)
 
   const clockid_t pidclock = MAKE_PROCESS_CPUCLOCK (pid, CPUCLOCK_SCHED);
 
-  int r = INTERNAL_SYSCALL_CALL (clock_getres, pidclock, NULL);
-  if (!INTERNAL_SYSCALL_ERROR_P (r))
+#ifndef __NR_clock_getres_time64
+# define __NR_clock_getres_time64 __NR_clock_getres
+#endif
+  int r = INTERNAL_SYSCALL_CALL (clock_getres_time64, pidclock, NULL);
+
+#ifndef __ASSUME_TIME64_SYSCALLS
+  if (r != 0 && r == -ENOSYS)
+    r = INTERNAL_SYSCALL_CALL (clock_getres, pidclock, NULL);
+#endif
+
+  if (r == 0)
     {
       *clock_id = pidclock;
       return 0;
     }
-
-  if (INTERNAL_SYSCALL_ERRNO (r) == EINVAL)
-    {
-      /* The clock_getres system call checked the PID for us.  */
-      return ESRCH;
-    }
-  else
-    return INTERNAL_SYSCALL_ERRNO (r);
+  if (r == -EINVAL)
+    /* The clock_getres system call checked the PID for us.  */
+    return ESRCH;
+  return -r;
 }
 
 versioned_symbol (libc, __clock_getcpuclockid, clock_getcpuclockid, GLIBC_2_17);