src: Align make output

The make inserts six spaces instead of four:

  GEN      access/viraccessapichecklxc.h
  GEN    hyperv/hyperv_wmi.generated.h
  GEN      access/viraccessapichecklxc.c
  GEN    hyperv/hyperv_wmi.generated.c
  GEN    hyperv/hyperv_wmi_classes.generated.typedef
  GEN    hyperv/hyperv_wmi_classes.generated.h
  GEN    hyperv/hyperv_wmi_classes.generated.c
  GEN      libvirt_access_qemu.xml
  GEN      libvirt_access.syms
  GEN      libvirt_access_lxc.xml
  GEN      libvirt_access_qemu.syms
  GEN      libvirt_access_lxc.syms
  GEN      libvirt_qemu.def
  GEN    esx/esx_vi_types.generated.typedef
  GEN    esx/esx_vi_types.generated.typeenum
  GEN    esx/esx_vi_types.generated.typetostring
  GEN    esx/esx_vi_types.generated.typefromstring
  GEN    esx/esx_vi_types.generated.h
  GEN    esx/esx_vi_types.generated.c
  GEN    esx/esx_vi_methods.generated.h
  GEN    esx/esx_vi_methods.generated.c
  GEN    esx/esx_vi_methods.generated.macro
  GEN    esx/esx_vi.generated.h
  GEN    esx/esx_vi.generated.c
  GEN      libvirt_lxc.def
Signed-off-by: NMichal Privoznik <mprivozn@redhat.com>