Apparently <delayimp.h> header changed since visual studio 2015 update 3 setting const to PfnDliHook
// Prior to Visual Studio 2015 Update 3, these hooks were non-const. They were
// made const to improve security (global, writable function pointers are bad).
// If for backwards compatibility you require the hooks to be writable, define
// the macro DELAYIMP_INSECURE_WRITABLE_HOOKS prior to including this header and
// provide your own non-const definition of the hooks.
Probably should include this in win_delay_load_hook.c source file
ifndef DELAYIMP_INSECURE_WRITABLE_HOOKS
define DELAYIMP_INSECURE_WRITABLE_HOOKS
endif