bug#40046: 28.0.50; infinite recursion futimens -> fdutimens -> futimens -> ...

[Mattias Engdegård]

On macOS 10.14, futimens in lib/futimens.c calls fdutimens in lib/utimens.c 
which calls futimens again, recursing until the stack is full. This cause 
Fcopy_file to crash, for instance.

No doubt I've made a silly configuration error, but I've wiped the 
(out-of-tree) build directory, regenerated configure and all. As expedience I 
commented out the futimens definition. Not sure how this is supposed to work 
really -- what am I missing? HAVE_FUTIMENS is set in config.h.