Completes the Implementation of the TLS-based errno

- Remove per-thread errno from the TCB structure (pterrno)
- Remove get_errno() and set_errno() as functions.  The macros are still available as stubs and will be needed in the future if we need to access the errno from a different address environment (KERNEL mode).
- Add errno value to the tls_info_s structure definitions
- Move sched/errno to libs/libc/errno.  Replace old TCB access to the errno with TLS access to the errno.

syscall/syscall.csv

@@ -28,7 +28,6 @@
 "fstatfs","sys/statfs.h","","int","int","FAR struct statfs *"
 "fsync","unistd.h","!defined(CONFIG_DISABLE_MOUNTPOINT)","int","int"
 "ftruncate","unistd.h","!defined(CONFIG_DISABLE_MOUNTPOINT)","int","int","off_t"
-"get_errno","errno.h","!defined(__DIRECT_ERRNO_ACCESS)","int"
 "getenv","stdlib.h","!defined(CONFIG_DISABLE_ENVIRON)","FAR char *","FAR const char *"
 "getgid","unistd.h","defined(CONFIG_SCHED_USER_IDENTITY)","gid_t"
 "getitimer","sys/time.h","!defined(CONFIG_DISABLE_POSIX_TIMERS)","int","int","FAR struct itimerval *"
@@ -143,7 +142,6 @@
 "send","sys/socket.h","defined(CONFIG_NET)","ssize_t","int","FAR const void *","size_t","int"
 "sendfile","sys/sendfile.h","defined(CONFIG_NET_SENDFILE)","ssize_t","int","int","FAR off_t *","size_t"
 "sendto","sys/socket.h","defined(CONFIG_NET)","ssize_t","int","FAR const void *","size_t","int","FAR const struct sockaddr *","socklen_t"
-"set_errno","errno.h","!defined(__DIRECT_ERRNO_ACCESS)","void","int"
 "setenv","stdlib.h","!defined(CONFIG_DISABLE_ENVIRON)","int","FAR const char *","FAR const char *","int"
 "setgid","unistd.h","defined(CONFIG_SCHED_USER_IDENTITY)","int","gid_t"
 "sethostname","unistd.h","","int","FAR const char *","size_t"