Description of problem:
Build failure with GCC6 because of unused variables,
introduced when disabling Allwinner AHCI and
gd-passthrough-i440FX support.

To work around the build failure, one can pass --disable-werror at
configure time.

Problem introduced with two commits:

 a41119d Disable igd-passthrough-i440FX
 8a9aadf Disable allwiner_ahci device

Version-Release number of selected component (if applicable):
Introduced in qemu-kvm-rhev-2.6.0-17.el7

How reproducible: 100% with GCC6

Steps to Reproduce:
1. Build with GCC6

Actual results:
<..>/qemu-kvm/hw/pci-host/piix.c:833:23: error: ‘igd_passthrough_i440fx_info’ defined but not used [-Werror=unused-const-variable=]
 static const TypeInfo igd_passthrough_i440fx_info = {

cc1: all warnings being treated as errors

and:

<..>/qemu-kvm/hw/ide/ahci.c:1804:23: error: ‘allwinner_ahci_info’ defined but not used [-Werror=unused-const-variable=]
 static const TypeInfo allwinner_ahci_info = {
                       ^~~~~~~~~~~~~~~~~~~
cc1: all warnings being treated as errors

Expected results:


Additional info: