Kill warn_unused_result warning in reel demo

debian/libnotcurses1.symbols

@@ -47,7 +47,7 @@ libnotcurses.so.1 libnotcurses1 #MINVER#
  ncplane_erase@Base 1.2.1
  ncplane_fadein@Base 1.2.1
  ncplane_fadeout@Base 1.2.1
- ncplane_format@Base 1.2.2
+ ncplane_format@Base 1.2.3
  ncplane_gradient@Base 1.2.1
  ncplane_greyscale@Base 1.2.1
  ncplane_hline_interp@Base 1.2.1
@@ -85,12 +85,12 @@ libnotcurses.so.1 libnotcurses1 #MINVER#
  ncplane_set_fg_rgb@Base 1.2.1
  ncplane_set_fg_rgb_clipped@Base 1.2.1
  ncplane_set_userptr@Base 1.2.1
- ncplane_stain@Base 1.2.2
+ ncplane_stain@Base 1.2.3
  ncplane_styles@Base 1.2.1
  ncplane_styles_off@Base 1.2.1
  ncplane_styles_on@Base 1.2.1
  ncplane_styles_set@Base 1.2.1
- ncplane_translate@Base 1.2.2
+ ncplane_translate@Base 1.2.3
  ncplane_translate_abs@Base 1.2.3
  ncplane_userptr@Base 1.2.1
  ncplane_visual_open@Base 1.2.1
@@ -147,7 +147,7 @@ libnotcurses.so.1 libnotcurses1 #MINVER#
  notcurses_resize@Base 1.2.1
  notcurses_stats@Base 1.2.1
  notcurses_stdplane@Base 1.2.1
- notcurses_stdplane_const@Base 1.2.2
+ notcurses_stdplane_const@Base 1.2.3
  notcurses_stop@Base 1.2.1
  notcurses_supported_styles@Base 1.2.1
  notcurses_top@Base 1.2.1

src/demo/reel.c

@@ -243,10 +243,11 @@ handle_input(struct notcurses* nc, struct ncreel* pr, int efd,
     }else{
       if(fds[0].revents & POLLIN){
         uint64_t eventcount;
-        read(fds[0].fd, &eventcount, sizeof(eventcount)); // drain eventfd
-        key = demo_getc_nblock(NULL);
-        if(key < 0){
-          return -1;
+        if(read(fds[0].fd, &eventcount, sizeof(eventcount)) > 0){
+          key = demo_getc_nblock(NULL);
+          if(key < 0){
+            return -1;
+          }
         }
       }
       if(fds[1].revents & POLLIN){