[sanitizer] use fewer size classes in the allocator to reduce the memory footprint. There is no all-size-fits-all constant here, but this change is positive or neutral on several large apps I've tested
Move tests that depend on -stats under 'requires asserts'

This fixes issues caused by the following commit:

  r176733 | jvoung | 2013-03-08 17:56:31 -0500
  Disable statistics on Release builds and move tests that depend on -stats.

Reported by: Jack Howarth <howarth@bromo.med.uc.edu>