The clang/llvm plugins pin annobin to a specific libLLVM soname, which
deadlocks the buildroot when llvm is rebased: the chroot cannot update
llvm while the installed annobin requires the old libLLVM, and annobin
cannot be erased because redhat-rpm-config requires it.
Disable both plugins on this branch and pass the negative configure flags
as well — the spec only ever passed --with-clang/--with-llvm, so configure
kept looking for clang++ and failed when the bconds were turned off.
Build this branch first, then rebuild annobin from c9-beta against the new
llvm.
