x86: Allow tracing of functions in arch/x86/kernel/rtc.c

Move native_read_tsc() to tsc.c to allow profiling to be
re-enabled for rtc.c.

Signed-off-by: David Vrabel <david.vrabel@citrix.com>
Cc: Peter Zijlstra <a.p.zijlstra@chello.nl>
Cc: Frederic Weisbecker <fweisbec@gmail.com>
Cc: Steven Rostedt <rostedt@goodmis.org>
Link: http://lkml.kernel.org/r/1349698050-6560-1-git-send-email-david.vrabel@citrix.com
Signed-off-by: Ingo Molnar <mingo@kernel.org>

arch/x86/kernel/tsc.c

@@ -77,6 +77,12 @@ unsigned long long
 sched_clock(void) __attribute__((alias("native_sched_clock")));
 #endif
 
+unsigned long long native_read_tsc(void)
+{
+	return __native_read_tsc();
+}
+EXPORT_SYMBOL(native_read_tsc);
+
 int check_tsc_unstable(void)
 {
 	return tsc_unstable;