sched: No PREEMPT_RT=y for all{yes,mod}config

While PREEMPT_RT is undoubtedly totally awesome, it does not, at this
time, make sense to have all{yes,mod}config select it.

Reported-by: Stephen Rothwell <sfr@canb.auug.org.au>
Fixes: 35772d6 ("sched: Enable PREEMPT_DYNAMIC for PREEMPT_RT")
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>

kernel/Kconfig.preempt

@@ -88,7 +88,7 @@ endchoice
 
 config PREEMPT_RT
 	bool "Fully Preemptible Kernel (Real-Time)"
-	depends on EXPERT && ARCH_SUPPORTS_RT
+	depends on EXPERT && ARCH_SUPPORTS_RT && !COMPILE_TEST
 	select PREEMPTION
 	help
 	  This option turns the kernel into a real-time kernel by replacing