score: Simplify <rtems/system.h>

Drop the <rtems/score/percpu.h> include since this file exposes a lot of
implementation details.

c/src/lib/libcpu/bfin/clock/clock.c

@@ -14,6 +14,7 @@
 #include <rtems.h>
 #include <stdlib.h>
 #include <rtems/libio.h>
+#include <rtems/score/percpu.h>
 #include <bsp.h>
 
 #include <libcpu/cecRegs.h>

c/src/lib/libcpu/or1k/shared/cache/cache.c

@@ -12,6 +12,7 @@
 #include <rtems/score/cpu.h>
 #include <rtems/score/interr.h>
 #include <rtems/score/or1k-utility.h>
+#include <rtems/score/percpu.h>
 #include <libcpu/cache.h>
 
 static inline void _CPU_OR1K_Cache_enable_data(void)

c/src/lib/libcpu/powerpc/mpc6xx/clock/c_clock.c

@@ -30,6 +30,7 @@
 #include <rtems/bspIo.h>                /* for printk() */
 #include <libcpu/powerpc-utility.h>
 #include <rtems/timecounter.h>
+#include <rtems/score/percpu.h>
 
 #include <bspopts.h>   /* for CLOCK_DRIVER_USE_FAST_IDLE */
 

c/src/lib/libcpu/powerpc/mpc6xx/mmu/pte121.c

@@ -63,6 +63,7 @@
 #ifndef DEBUG_MAIN
 #include <rtems.h>
 #include <rtems/bspIo.h>
+#include <rtems/score/percpu.h>
 #include <libcpu/cpuIdent.h>
 #include <libcpu/spr.h>
 #ifdef	DEBUG_EXC