fix regression: zero-init msghdr

- regressed in 9086834
- re-apply #8

Author: mikdusan

patch/linux-user__syscall.c.diff

@@ -1,5 +1,5 @@
 diff --git a/linux-user/syscall.c b/linux-user/syscall.c
-index 376629c68..88507fc17 100644
+index ccd3892b2..eb1a9dc5e 100644
 --- a/linux-user/syscall.c
 +++ b/linux-user/syscall.c
 @@ -134,6 +134,13 @@
@@ -16,6 +16,15 @@ index 376629c68..88507fc17 100644
  #ifndef CLONE_IO
  #define CLONE_IO                0x80000000      /* Clone io context */
  #endif
+@@ -3208,7 +3215,7 @@ static abi_long do_sendrecvmsg_locked(int fd, struct target_msghdr *msgp,
+                                       int flags, int send)
+ {
+     abi_long ret, len;
+-    struct msghdr msg;
++    struct msghdr msg = { 0 };
+     abi_ulong count;
+     struct iovec *vec;
+     abi_ulong target_vec;
 @@ -7273,9 +7280,20 @@ static inline abi_long host_to_target_timex64(abi_long target_addr,
  #define sigev_notify_thread_id _sigev_un._tid
  #endif