split "Peak vmm blocks" stats into vmcode and vmheap

The stats, esp the rstats, for vmm blocks should be updated to reflect which are in vmcode and which in vmheap, since that split (to be fair, the split was done recently, and the stats were added long long ago) is critical to understanding DR memory pressure:

                          Peak vmm blocks for heap :             14679
                         Peak vmm blocks for cache :              5139
                         Peak vmm blocks for stack :              9039
                  Peak vmm blocks for special heap :              4518
                  Peak vmm blocks for special mmap :              9043