(1) Implemented stack in runtime to keep dynamic node instance info, in case the

code enquires about its ancestor. Enables to run visc parboil benchmarks on x86
alone

(2) Modified unittests to have llvm.visc.init and cleanup intrinsics. Now they
all pass

(3) Modified visc.mk to easily compile visc version for just x86. Pass
TARGET=x86 as option to make command