2.6.0-test2-mm5 x86-64 link errors

[Patrick McLean <pmclean@cs.ubishops.ca>]

I get to play with an opteron for a bit, so I'm going to try 2.6 on it, 
but test2-mm5 seems to compile fine, but when it goes to link it, it 
gives these errors:

   LD      init/built-in.o
   LD      .tmp_vmlinux1
kernel/built-in.o(.text+0x359): In function `try_to_wake_up':
: undefined reference to `sched_clock'
kernel/built-in.o(.text+0x3b9): In function `try_to_wake_up':
: undefined reference to `sched_clock'
kernel/built-in.o(.text+0x1150): In function `load_balance':
: undefined reference to `sched_clock'
kernel/built-in.o(.text+0x1ae3): In function `schedule':
: undefined reference to `sched_clock'
kernel/built-in.o(.text+0x3a22): In function `move_task_away':
: undefined reference to `sched_clock'
kernel/built-in.o(.text+0x56cc): more undefined references to 
`sched_clock' follow
make: *** [.tmp_vmlinux1] Error 1