Function esp_idf_sys::ets_install_putc2

pub unsafe extern "C" fn ets_install_putc2(
    p: Option<unsafe extern "C" fn(c: c_char)>
)

@brief Ets_printf have two output functions： putc1 and putc2, both of which will be called if need ouput. To install putc2, which is defaulted installed as NULL.

@param void (*)(char) p: Output function to install.

@return None