Compile error on OSX:
```
/Users/stefan/Dev/neovim/src/os/io.c:34:13: error: static declaration of 'wait'
      follows non-static declaration
static void wait(bool *condition);
            ^
/usr/include/sys/wait.h:248:7: note: previous declaration is here
pid_t   wait(int *) __DARWIN_ALIAS_C(wait);
        ^
/Users/stefan/Dev/neovim/src/os/io.c:49:8: error: incompatible pointer types
      passing 'bool *' to parameter of type 'int *'
      [-Werror,-Wincompatible-pointer-types]
  wait(&running);
       ^~~~~~~~
/usr/include/sys/wait.h:248:17: note: passing argument to parameter here
pid_t   wait(int *) __DARWIN_ALIAS_C(wait);
                  ^
```