document that __builtin_malloc (etc) disrupt function call overrides since there is no function call

It seems that the main github page that offers the LD_PRELOAD (etc) methodologies should mention that if a library or the program itself optimize malloc() (etc) calls to their __builtin variants (for inlining), those calls won't be redirected to mimalloc.

In my particular case I'm trying to capture posix_memalign calls from a 3rd party lib and I suspect it was compiled with something like __builtin_posix_memalign. It took me hours to form this tentative conclusion so I think documentation would be appreciated.

While my conclusion is only tentative regarding posix_memalign (since my compiler doesn't have it), I did test that __builtin_malloc disrupts malloc.

EDIT: Even better, help users figure out how to turn off only allocation-related builtins for their compiler. E.g. -fno-builtin-malloc ... (etc)

Review the main GitHub page's LD_PRELOAD documentation and its explanation of allocation interception. Document that compiler-generated __builtin_malloc and related calls may not be redirected, and explain how allocation-related builtins can be disabled, including the -fno-builtin-malloc example. Done means users can understand this limitation and find the relevant compiler guidance.