#2 Fix for bdelta crash on creating large binary patch file

[Siarhei Siamashka]

bdelta can run out of stack when creating a large binary patch because it allocates some of the buffers on stack (copyloc1, copyloc2, copynum), changing allocation to heap helps to resolve the problem, a patch is attached.

I can't provide a testcase, because the source and destination files that got this problem triggered for me are quite big.

[Siarhei Siamashka]