additional question from "memcpy, strlen etc."

As an addition to the previous post by me, I have some pre-existing C code that I want to use in a Genode server I have created, and I don't really want to change this code. Currently, i'm not able to utilize functions like printf, memcpy etc in the C code i've written. What header files can I include to ensure that functions like memcpy and printf work in my code? From what I can see, the build process does not recognize the standard header files at all.

Peter