please find attached the PKGBUILD file. It's the one found in the AUR repository (http://aur.archlinux.org/packages/li/libguestfs/PKGBUILD) with a few small modifications:
I disabled the tests, because they failed, I used a hardcode java home path because the configuration script auto-detected this: /usr/lib/jvm/java-7-openjdk/jre and did complain for not finding /usr/lib/jvm/java-7-openjdk/jre/bin/javac
I updated the release (the old one failed as well).