patch 8.2.2919: using ":!command" does not work if it uses posix_spawn()

Problem:    Using ":!command" does not work if the command uses posix_spawn().
Solution:   Do not call ioctl() with TIOCSCTTY. (Felipe Contreras)

src/os_unix.c

@@ -4775,11 +4775,6 @@ mch_call_shell_fork(
 		    // push stream discipline modules
 		    if (options & SHELL_COOKED)
 			setup_slavepty(pty_slave_fd);
-#  ifdef TIOCSCTTY
-		    // Try to become controlling tty (probably doesn't work,
-		    // unless run by root)
-		    ioctl(pty_slave_fd, TIOCSCTTY, (char *)NULL);
-#  endif
 		}
 # endif
 		set_default_child_environment(FALSE);

src/version.c

@@ -750,6 +750,8 @@ static char *(features[]) =
 
 static int included_patches[] =
 {   /* Add new patch number below this line */
+/**/
+    2919,
 /**/
     2918,
 /**/