Returns true if the named file has the setgid bit set.
/*
* call-seq:
* File.setgid?(file_name) => true or false
*
* Returns <code>true</code> if the named file has the setgid bit set.
*/
static VALUE
test_sgid(obj, fname)
VALUE obj, fname;
{
#ifdef S_ISGID
return check3rdbyte(fname, S_ISGID);
#else
return Qfalse;
#endif
}