Teach `-dgc2stack` to promote GC allocations in simple loops to stack allocations too. (A "simple" loop is one where the allocation isn't used in a subsequent iteration) This also means it's no longer necessary to run this pass multiple times. Running it once after inlining should now catch all cases.

#ifndef LDC_GEN_PROGRAMS_H
#define LDC_GEN_PROGRAMS_H

#include "llvm/System/Path.h"

llvm::sys::Path getGcc();

#endif