w64: Fix TCG helper functions with 5 arguments

w64: Fix TCG helper functions with 5 arguments

TCG uses 6 registers for function arguments on 64 bit Linux hosts,
but only 4 registers on W64 hosts.

Commit 2999a0b20074a7e4a58f56572bb1436749368f59 increased the number
of arguments for some important helper functions from 4 to 5
which triggered a bug for W64 hosts: QEMU aborts when executing
helper_lcall_real in the guest's BIOS because function
tcg_target_get_call_iarg_regs_count always returned 6.

As W64 has only 4 registers for arguments, the 5th argument must be
passed on the stack using a correct stack offset.

Signed-off-by: Stefan Weil <sw@weilnetz.de>
Signed-off-by: Aurelien Jarno <aurelien@aurel32.net>
Signed-off-by: Michael Roth <mdroth@linux.vnet.ibm.com>