Cannot compile C file using ImportC

[rempas]

So I'm trying to compile the 
[toml99](https://github.com/cktan/tomlc99) C library with DMD 
using ImportC. I first preprocessed the file using `cproc`. The 
reason I didn't used GCC is because it defines some symbols 
specific to GCC so it will furthermore mess the compilation 
process. I created a gist of the file and uploaded 
[here](https://gist.github.com/rempas/a1633ba4d3fd4f166277d7ff35cedc63) in case someone wants to get the file and try it. The error message I'm getting is the following:

```
toml.c(39): Error: cannot implicitly convert expression `malloc` 
of type `extern (C) void*(ulong __size)` to `extern (C) void* 
function(ulong)`
toml.c(40): Error: cannot implicitly convert expression `free` of 
type `extern (C) void(void* __ptr)` to `extern (C) void 
function(void*)`
```

These two symbols are function pointers but I wasn't able to 
modify and make it work. Any ideas?