support different number of size classes at runtime

With TCMALLOC_TRANSFER_NUM_OBJ environment variable we can change
transfer batch size. And with that comes slightly different number of
size classes depending on value of transfer batch size.

We used to have hardcoded number of size classes, so we couldn't
really support any batch size setting.

This commit adds support for dynamic number of size classes (runtime
value returned by Static::num_size_classes()).
9 files changed