test: Duplicate existing recvfrom() valgrind suppression for recv()

Some architectures, including i686, actually have a recv() system
call, not just a recvfrom(), and we need to cover the recv() with
MSG_TRUNC into a NULL buffer for them as well.

Signed-off-by: Stefano Brivio <sbrivio@redhat.com>
Reviewed-by: David Gibson <david@gibson.dropbear.id.au>

test/valgrind.supp

@@ -6,3 +6,12 @@
    ...
    fun:tcp_sock_consume
 }
+
+# same as above, for architectures with the recv() system call (at least i686):
+{
+   passt_recv_MSG_TRUNC_into_NULL_buffer
+   Memcheck:Param
+   socketcall.recv(buf)
+   ...
+   fun:tcp_sock_consume
+}