Function dt_printf

* This function handles all output from libdtrace, as well as the * dtrace_sprintf() case. If we're here due to dtrace_sprintf(), then * dt_sprintf_buflen will be non-zero; in this case, we sprintf into the * specified buffer and return. Otherwise, if output is buffered (denoted by * a NULL fp), we sprintf the desired output into the buffered buffer * (expanding the buffer if required). If