use Ticks not MACHP(0)->ticks as the amd64 port will not
have ticks as part of the Mach structure.

Reference: /n/atom/patch/applied2013/fsconuseticks
Date: Mon Aug 26 05:03:12 CES 2013
Signed-off-by: quanstro@quanstro.net

--- /sys/src/fs/port/con.c	Mon Aug 26 05:02:48 2013
+++ /sys/src/fs/port/con.c	Mon Aug 26 05:02:49 2013
@@ -654,7 +654,7 @@
 cmd_version(int, char *[])
 {
 
-	print("%d-bit %s as of %T\n", sizeof(Off)*8 - 1, service, mktime);
+	print("%d-bit %s compiled %T\n", sizeof(Off)*8 - 1, service, mktime);
 	print("\tlast boot %T\n", boottime);
 }
 
@@ -742,7 +742,7 @@
 	Timet t1, t2;
 	int i;
 
-	t1 = MACHP(0)->ticks;
+	t1 = Ticks;
 	conline[0] = 0;
 	for(i=1; i<argc; i++) {
 		strcat(conline, " ");