Fix build errors, add <sched.h> header file:

Fix build errors, add <sched.h> header file:

kernel/synchro-test.c: In function 'sched':
kernel/synchro-test.c:220: error: implicit declaration of function 'schedule'
kernel/synchro-test.c: In function 'mutexer':
kernel/synchro-test.c:227: error: implicit declaration of function 'daemonize'
kernel/synchro-test.c:228: error: implicit declaration of function 'set_user_nice'
kernel/synchro-test.c:241: error: dereferencing pointer to incomplete type
kernel/synchro-test.c: In function 'semaphorer':
kernel/synchro-test.c:263: error: dereferencing pointer to incomplete type
kernel/synchro-test.c: In function 'reader':
kernel/synchro-test.c:287: error: dereferencing pointer to incomplete type
kernel/synchro-test.c: In function 'writer':
kernel/synchro-test.c:311: error: dereferencing pointer to incomplete type
kernel/synchro-test.c: In function 'downgrader':
kernel/synchro-test.c:340: error: dereferencing pointer to incomplete type

Signed-off-by: Randy Dunlap <randy.dunlap@oracle.com>
Acked-by: David Howells <dhowells@redhat.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>