compiling closure.c
closure.c:264:14: error: implicit declaration of function 'ffi_prep_closure' is invalid in C99 [-Werror,-Wimplicit-function-declaration]
	result = ffi_prep_closure(pcl, cif, callback, (void *)self);
			 ^
1 error generated.
make[2]: *** [closure.o] Error 1
make[1]: *** [ext/fiddle/all] Error 2
make: *** [build-ext] Error 2

$ git clone https://github.com/postmodern/ruby-install.git
$ cd ruby-install
$ ./bin/ruby-install ruby 2.7.1 -c -- --with-arch=arm64 --prefix=$(rbenv root)/versions/2.7.1-arm64 CFLAGS=-DUSE_FFI_CLOSURE_ALLOC=1