Replace deprecated malloc_hook
This replaces the use of the deprecated __malloc_hook with dlsym based on the example in https://www.slideshare.net/tetsu.koba/tips-of-malloc-free slides 30-33.
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This replaces the use of the deprecated __malloc_hook with dlsym based on the example in https://www.slideshare.net/tetsu.koba/tips-of-malloc-free slides 30-33.