Motivation: http://llvm.org/bugs/show_bug.cgi?id=18407
External projects, for example dragonegg, would be affected when pass is added.
This patch introduces libLLVMAllPasses.a in lib/Transforms.
Even without LLVM_LINKALLPASSES_IFACE, everything would work fine.
I introduce LLVM_LINKALLPASSES_IFACE to make inter-object dependency scaning easier.
I expect clang can be built regardless of this patch.