Travis Tilley authored May 27, 2015 and Natanael Copa committed Jun 01, 2015

clean up and update patchset
switch to cmake
perform a two-stage build with a minimal bootstrap compile of clang
add clang extras
update package list to split out clang documentation
enable pulling from the svn release tags
fix making use of abuild CFLAGS/CXXFLAGS during build
don't run check-llvm, as the tests fail when running under PaX

(cherry picked from commit 08fdc970)

fixes #4235