arch pkgbuild - direct git download - prototype (rough)

Archers, Please look at the attached PKGBUILD for libart-lgpl. It pulls the source either directly from the git tree on the local machine (after updating it), or it clones directly from scm.trinitydesktop.org. I looked over the existing pkgbuilds that use git in one form or another in ABS and this is my prototype for how we could do the remaining build scripts. Let me know what changes you propose. -- David C. Rankin, J.D.,P.E.