I'm playing with supporting custom stack map formats with statepoints. While
doing so, I noticed that the existing implementation didn't indicate inherently
unsized frames. This change essentially just ports the functionality that already
exists for the default StackMaps section to custom stackmaps.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@233891 91177308-0d34-0410-b5e6-96231b3b80d8
