ui/input-linux: Do not ignore ioctl() return value

ui/input-linux: Do not ignore ioctl() return value

Fix warnings reported by Clang static code analyzer:

    CC      ui/input-linux.o
      ui/input-linux.c:343:9: warning: Value stored to 'rc' is never read
          rc = ioctl(il->fd, EVIOCGBIT(EV_REL, sizeof(relmap)), &relmap);
          ^    ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
      ui/input-linux.c:351:9: warning: Value stored to 'rc' is never read
          rc = ioctl(il->fd, EVIOCGBIT(EV_ABS, sizeof(absmap)), &absmap);
          ^    ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
      ui/input-linux.c:354:13: warning: Value stored to 'rc' is never read
              rc = ioctl(il->fd, EVIOCGABS(ABS_X), &absinfo);
              ^    ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
      ui/input-linux.c:357:13: warning: Value stored to 'rc' is never read
              rc = ioctl(il->fd, EVIOCGABS(ABS_Y), &absinfo);
              ^    ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
      ui/input-linux.c:365:9: warning: Value stored to 'rc' is never read
          rc = ioctl(il->fd, EVIOCGBIT(EV_KEY, sizeof(keymap)), keymap);
          ^    ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
      ui/input-linux.c:366:9: warning: Value stored to 'rc' is never read
          rc = ioctl(il->fd, EVIOCGKEY(sizeof(keystate)), keystate);
          ^    ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

Reported-by: Clang Static Analyzer
Signed-off-by: Philippe Mathieu-Daudé <philmd@redhat.com>
Reviewed-by: Darren Kenny <darren.kenny@oracle.com>
Message-id: 20200322161219.17757-1-philmd@redhat.com
Signed-off-by: Gerd Hoffmann <kraxel@redhat.com>