Re: [PATCH 1/2] tree-diff: fix leak when not HAVE_ALLOCA

Carlo Marcelo Arenas Belón  [off-list ref] writes:

b8ba412bf7 (tree-diff: avoid alloca for large allocations, 2016-06-07)
adds a way to route some bigger allocations out of the stack and free
them through the addition of two conveniently named macros, but leaves
the calls to free the xalloca part, which could be also in the heap,
if the system doesn't HAVE_ALLOCA (ex: macOS).

Nicely spotted and analyzed.  Thanks.