library: uptime API changes

Removed the printf_uptime, binaries can do printf easily enough.
sprint_uptime split into two as there wasn't a lot of common
code
 sprint_uptime(): old style uptime line
 sprint_uptime_short(): short new style "uptime -p"

Hertz_hack needed this, no sane system uses the code (I think)
so just assume 100 like we do in FreeBSD.

uptime.c

@@ -28,7 +28,7 @@
 #include "fileutils.h"
 #include "nls.h"
 #include "proc/sysinfo.h"
-#include "proc/whattime.h"
+#include <proc/uptime.h>
 #include "proc/version.h"
 
 static void print_uptime_since()
@@ -104,6 +104,9 @@ int main(int argc, char **argv)
 			usage(stderr);
 		}
 
-	print_uptime(p);
+	if (p)
+	    printf("%s\n", sprint_uptime());
+	else
+	    printf("%s\n", sprint_uptime_short());
 	return EXIT_SUCCESS;
 }