Treat the boot loader as the same as the kernel for what's visible

The boot loader will be growing some (limited) support for some kernel
interfaces for some of the timekeeping routines to support zstd code.
Allow the declarations for them to be visible when compiling for the
boot loader, rather than treating it like a user-space environment
(which stand.h already provides to a limited degree).

sys/sys/time.h

@@ -492,7 +492,7 @@ struct clockinfo {
 #define	CPUCLOCK_WHICH_TID	1
 #endif
 
-#ifdef _KERNEL
+#if defined(_KERNEL) || defined(_STANDALONE)
 
 /*
  * Kernel to clock driver interface.
@@ -600,7 +600,7 @@ int	tvtohz(struct timeval *tv);
 	(((sbt2) >= sbt_timethreshold) ?				\
 	    ((*(sbt) = getsbinuptime()), 1) : ((*(sbt) = sbinuptime()), 0))
 
-#else /* !_KERNEL */
+#else /* !_KERNEL && !_STANDALONE */
 #include <time.h>
 
 #include <sys/cdefs.h>