Leveraging poolalloc's data structure analysis.
* To use, must configure with --enable-dsa,
* Specify poolalloc location with --with-poolalloc{src,obj},
* Run opt with -load {LLVMDataStructure,poolalloc}.{so,dylib}, whether or not
  DSA will be used (otherwise dynamic linking will fail)
* Run opt with -use-dsa as well to actually use DSA rather than basic-AA.