Fix type of previous_layer_frame_avail to avoid MSVC warning.

Change-Id: Iea05a93a48a1274341ff74869e18b047b6a55e55
diff --git a/examples/svc_encoder_rtc.cc b/examples/svc_encoder_rtc.cc
index a531d33..ad40132 100644
--- a/examples/svc_encoder_rtc.cc
+++ b/examples/svc_encoder_rtc.cc
@@ -1809,7 +1809,7 @@
     // Loop over spatial layers.
     for (int slx = 0; slx < ss_number_layers; slx++) {
       if (slx > 0 && app_input.input_ctx[slx].filename != NULL) {
-        const bool previous_layer_frame_avail = frame_avail;
+        const int previous_layer_frame_avail = frame_avail;
         frame_avail = read_frame(&(app_input.input_ctx[slx]), &raw);
         if (previous_layer_frame_avail != frame_avail) {
           die("Mismatch in number of frames between spatial layer input files");