qemu-ga: Building Windows MSI installation with configure/Makefile

New options were added to enable Windows MSI installation package
creation:

Option --enable-guest-agent-msi, like the name suggests, enables building
Windows MSI package for QEMU guest agent; option --disable-guest-agent-msi
disables MSI package creation; by default, no MSI package is created

Signed-off-by: Yossi Hindin <yhindin@redhat.com>
Message-Id: <1430913460-13174-5-git-send-email-yhindin@redhat.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>