Fix up some problems/issues remaining from PR 1007

1. Add missing conditional logic in include/sys/syscall_lookup.h
2. CONFIG_NPTHREAD_KEYS removed from code but was still in sched/Kconfig
3. Refresh all configurations affected by PR 1007
4. syscall/syscall_funclookup.c needs to include nuttx/tls.h

include/sys/syscall_lookup.h

@@ -283,8 +283,10 @@ SYSCALL_LOOKUP(telldir,                    1)
   SYSCALL_LOOKUP(shmdt,                    1)
 #endif
 
+#if CONFIG_TLS_NELEM > 0
   SYSCALL_LOOKUP(tls_alloc,                0)
   SYSCALL_LOOKUP(tls_free,                 1)
+#endif
 
 /* The following are defined if pthreads are enabled */