slock dynamic psword input indicator

config:
```
// Date display settings
static const char *pswind_font = "Liberation Sans Mono:style=Regular:size=16";
static const char *pswind_color = "#ffffff";
static const int pswind_y_off = 0; // pixels relative to center
```
readpw() part:
```
            // if len > 0 -> password input, if resetcolor -> media keys || escape pressed, else -> failed passwored input
            color = len ? INPUT : resetcolor ? INIT : ((failure || failonclear) ? FAILED : INIT);
            if (resetcolor) { --resetcolor; };
            if (running) {
                pthread_mutex_lock(&mutex);
                for (screen = 0; screen < nscreens; screen++) {
                    if (oldc != color){
                        XSetWindowBackground(dpy,
                                             locks[screen]->win,
                                             locks[screen]->colors[color]);
                        XClearWindow(dpy, locks[screen]->win);
                        /* Redraw time  and date after screen cleared */
                        draw_time(dpy, locks[screen]);
                        draw_date(dpy, locks[screen]);
                    };
                    draw_pswind(dpy, locks[screen], failure);
                }
                if (failure) { --failure; };
                pthread_mutex_unlock(&mutex);
                oldc = color;
            }
```
draw_pswind():
```
static unsigned long prrnum = 0;
static void draw_pswind(Display *dpy, struct lock *lock, int failure) {
    char pswindstr[25];
    if (failure) {
        snprintf(pswindstr, sizeof(pswindstr), "✕✕✕✕✕✕✕✕");
    } else {
        unsigned long rnum;
        if (getrandom(&rnum,sizeof(rnum),0) != sizeof(rnum)){
            srandom(time(NULL));
            rnum = random();
        };
        rnum &= 0xFF;

        if (prrnum == rnum) {
            ++rnum;
        };
        prrnum = rnum;

        char *sym[] = {"●", "⚫"}; // {"▪", "■"};
        snprintf(pswindstr, sizeof(pswindstr), "%s%s%s%s%s%s%s%s",
                 sym[(rnum >> 0) & 1], sym[(rnum >> 1) & 1],
                 sym[(rnum >> 2) & 1], sym[(rnum >> 3) & 1],
                 sym[(rnum >> 4) & 1], sym[(rnum >> 5) & 1],
                 sym[(rnum >> 6) & 1], sym[(rnum >> 7) & 1]);
    };

    XGlyphInfo ext;
    XftTextExtentsUtf8(dpy, pswindfont, (FcChar8*)pswindstr, strlen(pswindstr), &ext);
    int pswind_x = (lock->w - ext.xOff) / 2;
    int pswind_y = ((lock->h/6) * 5) + pswind_y_off;
    XClearArea(dpy, lock->win, pswind_x, pswind_y - pswindfont->ascent, ext.xOff,
               pswindfont->ascent + pswindfont->descent, False);
    XftDrawStringUtf8(lock->xftdraw, &lock->picol, pswindfont, pswind_x, pswind_y,
                      (FcChar8*)pswindstr, strlen(pswindstr));
    XFlush(dpy);
}
```