This is the second stage libc.
The additions here are minimal. We implement the few extra things we need to make cc and cci/1 work. Without the cc driver bootstrapped yet, it's a pain to build C files so we only implement what we need.
We now have a real malloc() and free() that reclaims memory. This is especially important for our compiler which does a lot of string and type allocation.
This stage is structured as an overlay over the first stage. Files in src/ (such as malloc.c) replace files in the previous stage with the same name (such as malloc.oo.) The build process for this stage libc compiles the files in src/, then combines the resulting object files with those from the previous stage into a static library.
Note: omC doesn't support unsigned so, when compiling code with the first stage compiler, size_t is signed! This libc is also used with the later stage compilers where size_t is properly unsigned. See include/__onramp/__size_t.h.