linux-user: Mark cpu_loop() with noreturn attribute

cpu_loop() never exits, so mark it with QEMU_NORETURN.

Reviewed-by: Richard Henderson <richard.henderson@linaro.org>
Reviewed-By: Warner Losh <imp@bsdimp.com>
Reviewed-by: Bin Meng <bmeng.cn@gmail.com>
Signed-off-by: Philippe Mathieu-Daudé <f4bug@amsat.org>
Reviewed-by: Warner Losh <imp@bsdimp.com>
Message-Id: <20211106113916.544587-1-f4bug@amsat.org>
Signed-off-by: Laurent Vivier <laurent@vivier.eu>
diff --git a/linux-user/user-internals.h b/linux-user/user-internals.h
index f71f372..a8fdd69 100644
--- a/linux-user/user-internals.h
+++ b/linux-user/user-internals.h
@@ -64,7 +64,7 @@
                     abi_long arg5, abi_long arg6, abi_long arg7,
                     abi_long arg8);
 extern __thread CPUState *thread_cpu;
-void cpu_loop(CPUArchState *env);
+void QEMU_NORETURN cpu_loop(CPUArchState *env);
 const char *target_strerror(int err);
 int get_osversion(void);
 void init_qemu_uname_release(void);