ipc_msg.c: fix multiple personalities support in msgrcv ipc subcall
ipc_msg.c: fix multiple personalities support in msgrcv ipc subcall

When msgrcv syscall is an ipc subcall, msgp (pointer to struct msgbuf)
and msgtyp (message type) syscall arguments are passed via proxy
structure which definition significantly depends on tracee's
wordsize.

* ipc_msg.c (fetch_msgrcv_args): New function.
(sys_msgrcv): Use it.

kapdop/android_external_strace,cuviper/strace,Distrotech/strace,cuviper/strace,Saruta/strace,Saruta/strace,kapdop/android_external_strace,Saruta/strace,Distrotech/strace,Saruta/strace,vrastogi/strace,kapdop/android_external_strace,Distrotech/strace,cuviper/strace,vrastogi/strace,vrastogi/strace,kapdop/android_external_strace,cuviper/strace,cuviper/strace,vrastogi/strace,Saruta/strace,Distrotech/strace,vrastogi/strace,kapdop/android_external_strace,Distrotech/strace