The variable "environ" shows as undeclared

[rempas at tutanota.com]

I'm trying to compile the Tiny C Compiler (thanks for your help to my previous email)
and I'm getting an error message saying that the "environ" variable is undeclared.
I made my research and I found out that it exists on DragonFlyBSD's libc. So anyone
knows why I'm getting this error? Maybe I need a development package and I don't know? 
I tried to compile with GCC and Clang.

The source to the Tiny C compiler for everyone that wants to try:
https://repo.or.cz/tinycc.git

The exact error message:
```
tccrun.c:154:19: error: 'environ' undeclared (first use in this function)
         char **envp = environ;
                                    ^~~~~~~
```