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.

#!/bin/sh

g++ llvm-ext.cpp -c `llvm-config --cxxflags`
g++ llvm-opt.cpp -c `llvm-config --cxxflags`
g++ llvm-typemonitor.cpp -c `llvm-config --cxxflags`

rm -f libllvm-c-ext.a
ar rc libllvm-c-ext.a llvm-ext.o llvm-opt.o llvm-typemonitor.o
ranlib libllvm-c-ext.a