Update bindings to libvirt 8

[mpontillo]

Now that our upstream changes have landed in c-for-go, go-libvirt's libvirt bindings can be updated to support libvirt v8.0.0.

Note that we are roughly following the Ubuntu LTS release cycle with regard to the libvirt version supported; I plan to update to test with v10.0.0 next.

[trapgate]

I think the gen-consts script can be simplified somewhat, and install-c-for-go.sh can then be dropped.

Here's my suggested version of gen-consts.sh:

#!/bin/bash
#
# This runs the first code generator used by go-libvirt: c-for-go. This script
# is run from the 'go generate ./...' command, and only needs to be run when
# changing to a different version of libvirt.

# Set TOP to the root of this repo, and SCRIPTS to the absolute path to the 
# scripts/ directory.
TOP="$( cd "$( dirname "${BASH_SOURCE[0]}" )/.." && pwd )"
SCRIPTS="$( cd "$( dirname "${BASH_SOURCE[0]}" )" && pwd )"

if [ -z "${LIBVIRT_SOURCE}" ]; then
    echo "Set LIBVIRT_SOURCE to the root of the libvirt sources you want to use first."
    exit 1
fi
if [ -z "$GOBIN" ]; then
    export GOBIN=$TOP/bin
fi

# Make sure c-for-go is installed
echo "Attempting to install c-for-go..."
if ! go install github.com/xlab/[email protected] ; then
    echo "failed to install c-for-go."
    exit 1
fi

# Make sure goyacc is installed (needed for the lvgen/ generator)
echo "Attempting to install goyacc..."
if ! go install golang.org/x/tools/cmd/[email protected]; then
    echo "failed to install goyacc. Please install it manually from https://golang.org/x/tools/cmd/goyacc"
    exit 1
fi

# Ensure fresh output is in libvirt/
rm -rf libvirt/

# Temporarily symlink the libvirt sources to a subdirectory because c-for-go
# lacks a mechanism for us to pass it a search path for header files.
LVDIR=lv_source
ln -sF ${LIBVIRT_SOURCE} ${LVDIR}
if ! c-for-go -nostamp -nocgo -ccincl libvirt.yml; then
    echo "c-for-go failed"
    exit 1
fi
mv libvirt/const.go ${SCRIPTS}/../const.gen.go
rm ${LVDIR}

[trapgate]

You can drop the install-c-for-go.sh script now, I think.