Add sizes for free() in zlib

Add sizes for free() in zlib

Rebased version of a diff from miod who described it as follows:

This tries to keep diffability against upstream, hence a questionable
choice of the size type for zcfree() - but all sizes should fit in 32
bits anyway.

Since all zcfree routines used in the tree cope with NULL arguments
(including the various alloc.c used by the boot blocks), I have
simplified TRY_FREE to compensate for the growth.

Reminded by and ok mpi