libc: add clock_getres()/clock_gettime() system calls.

In order to make it more clear that ticks should be used for timers
and realtime should be used for timestamps / displaying the date/time,
getuptime() was renamed to getticks() and getuptime2() was renamed to
getuptime().

Servers, drivers, libraries, tests, etc that use getuptime()/getuptime2()
have been updated. In instances where a realtime was calculated, the
calculation was changed to use realtime.

System calls clock_getres() and clock_gettime() were added to PM/libc.

sys/sys/time.h

@@ -248,11 +248,12 @@ struct	itimerspec {
 	struct	timespec it_value;
 };
 
-#ifndef __minix
 #define	CLOCK_REALTIME	0
+#define	CLOCK_MONOTONIC	3
+
+#ifndef __minix
 #define	CLOCK_VIRTUAL	1
 #define	CLOCK_PROF	2
-#define	CLOCK_MONOTONIC	3
 #endif
 
 #if defined(_NETBSD_SOURCE)