delay start of memory checking

_From [derek.br...@gmail.com](https://code.google.com/u/117968039472581148324/) on December 10, 2010 17:57:53_

PR 424531

If the heap walk (for PR 406722/PR 415179) works, we can "delay start"
DrMemory's instrumentation. Wait for initialization to finish and then
do a memory, heap, and thread walk and start there. Won't catch bugs
that involve uninit memory from init time: but that's the tradeoff,
getting faster startup at cost of potential false neg. Once in
steady-state, for most apps our slowdowns should be better than
init slowdowns.

_Original issue: http://code.google.com/p/drmemory/issues/detail?id=130_