non-nil, even if the function call is successful. Unlike normal Go conventions,
you should first check whether the call succeeded before checking the error
result. For example:

	n, err := C.setenv(key, value, 1)
	if n != 0 {
		// we know the call failed, so it is now valid to use err
		return err
	}

Calling C function pointers is currently not supported, however you can

pkg os, func Readlink(string) (string, error)
pkg os, func Remove(string) error
pkg os, func RemoveAll(string) error
pkg os, func Rename(string, string) error
pkg os, func SameFile(FileInfo, FileInfo) bool
pkg os, func Setenv(string, string) error
pkg os, func StartProcess(string, []string, *ProcAttr) (*Process, error)
pkg os, func Stat(string) (FileInfo, error)
pkg os, func Symlink(string, string) error
pkg os, func TempDir() string