semihosting: remove the pthread include which seems unused

This have been introduced by:
  8de702cb677c8381fb702cae252d6b69aa4c653b

It doesn't seem to be used so remove it.

Signed-off-by: KONRAD Frederic <frederic.konrad@adacore.com>
Reviewed-by: Philippe Mathieu-Daudé <philmd@redhat.com>
Acked-by: Alex Bennée <alex.bennee@linaro.org>
Message-Id: <1589806958-23511-1-git-send-email-frederic.konrad@adacore.com>
Signed-off-by: Laurent Vivier <laurent@vivier.eu>

hw/semihosting/console.c

@@ -23,7 +23,6 @@
 #include "exec/exec-all.h"
 #include "qemu/log.h"
 #include "chardev/char.h"
-#include <pthread.h>
 #include "chardev/char-fe.h"
 #include "sysemu/sysemu.h"
 #include "qemu/main-loop.h"