[ET Trac] [Einstein Toolkit] #1566: Update Cactus autoconf

#1566: Update Cactus autoconf ----------------------+----------------------------------------------------- Reporter: eschnett | Owner: Type: defect | Status: new Priority: major | Milestone: Component: Cactus | Version: development version Keywords: | ----------------------+----------------------------------------------------- We are using autoconf 2.13 for Cactus. This release is by now 15 years old and doesn't support Fortran (nor modern C++ features). It is time to update.