pthread_attr_setschedpolicy/2-1.c: simplify error handling

Remove all gotos and if there's error in any of pthread
functions exit immediately.

Signed-off-by: Jan Stancek <jstancek@redhat.com>
pthread_attr_setschedpolicy/2-1.c: fix race at thread startup

Test can hang during startup in following scenario:

                    main                                       new thread
--------------------------------------------------+-------------------------------------
int create_thread(int prio, pthread_t * tid)      |
...                                               |
    pthread_create(tid, &attr, thread_func, NULL);|
        while (!thread_started) {                 |
                                                  |   void *thread_func(void *data)
                                                  |        thread_started = 1;
                                                  |        pthread_cond_signal(&cond);
            pthread_mutex_lock(&c_mutex);         |
132:        pthread_cond_wait(&cond, &c_mutex);   |
                                                  |65:     pthread_mutex_lock(&mutex);
                                                  |

(gdb) bt
 #0  0x00007fd588808f6d in __lll_lock_wait () from /lib64/libpthread.so.0
 #1  0x00007fd588804d31 in _L_lock_790 () from /lib64/libpthread.so.0
 #2  0x00007fd588804c37 in pthread_mutex_lock () from /lib64/libpthread.so.0
 #3  0x0000000000400bba in thread_func (data=0x0) at ../../../conformance/interfaces/pthread_attr_setschedpolicy/2-1.c:65
 #4  0x00007fd588802de3 in start_thread () from /lib64/libpthread.so.0
 #5  0x00007fd5885300dd in clone () from /lib64/libc.so.6
(gdb) t 2
(gdb) bt
 #0  0x00007fd5888066f5 in pthread_cond_wait@@GLIBC_2.3.2 () from /lib64/libpthread.so.0
 #1  0x0000000000400d9b in create_thread (prio=5, tid=0x7fffdb562678) at ../../../conformance/interfaces/pthread_attr_setschedpolicy/2-1.c:132
 #2  0x0000000000400e82 in main () at ../../../conformance/interfaces/pthread_attr_setschedpolicy/2-1.c:174

Fix this by using same c_mutex in thread_func for updating
thread_started and signalling cond.

Signed-off-by: Jan Stancek <jstancek@redhat.com>
pthread_attr_setschedpolicy/2-1.c: bind threads to single CPU

To make sure that threads are blocked on mutex, bind all to single CPU.
Because they all use SCHED_FIFO policy with main thread having the lowest
priority, main will progress only after three created threads block on
mutex.

Signed-off-by: Jan Stancek <jstancek@redhat.com>