<sched.h>: Add sched_getcpu() and cpu_set_t

This adds the cpu_set_t type definition and related functions
and macros used to handle CPU thread affinity.

  sched_getcpu()
  sched_setaffinity()
  sched_getaffinity()

Change-Id: If382ecafde8926341a88478062b275553645065b
diff --git a/libc/SYSCALLS.TXT b/libc/SYSCALLS.TXT
index 0a08e12..2bb8a42 100644
--- a/libc/SYSCALLS.TXT
+++ b/libc/SYSCALLS.TXT
@@ -229,6 +229,9 @@
 int sched_get_priority_max(int policy)  159
 int sched_get_priority_min(int policy)  160
 int sched_rr_get_interval(pid_t pid, struct timespec *interval)  161
+int sched_setaffinity(pid_t pid, size_t setsize, const cpu_set_t* set) 241
+int __sched_getaffinity:sched_getaffinity(pid_t pid, size_t setsize, cpu_set_t* set)  242
+int __getcpu:getcpu(unsigned *cpu, unsigned *node, void *unused) 345,318,318
 
 # io priorities
 int ioprio_set(int which, int who, int ioprio) 314,289,288