memcpy should use our implementation

[tari]

GCC can often inline memcpy, but we also currently rename it to sys_memcpy to avoid potential recursive invocation (wherein it optimizes the implementation to a call to memcpy). The syscall seems to sometimes behave incorrectly; we should provide a version of memcpy built with appropriate options to avoid recursing.

GCC manual suggests building that particular module with -ffreestanding and implementing memcpy, memmove, memset and memcmp should be good.

[tari]

Fixed by d1d30ce.