Remove LOGC()

It is not clear when to use LOGC() rather than LOGE(). Always use
LOGE().

Moreover, enum sc_log_level has no "critical" log level.

app/src/usb/aoa_hid.c

@@ -278,7 +278,7 @@ sc_aoa_start(struct sc_aoa *aoa) {
 
     bool ok = sc_thread_create(&aoa->thread, run_aoa_thread, "scrcpy-aoa", aoa);
     if (!ok) {
-        LOGC("Could not start AOA thread");
+        LOGE("Could not start AOA thread");
         return false;
     }
 

app/src/usb/scrcpy_otg.c

@@ -56,7 +56,7 @@ scrcpy_otg(struct scrcpy_options *options) {
 
     // Minimal SDL initialization
     if (SDL_Init(SDL_INIT_EVENTS)) {
-        LOGC("Could not initialize SDL: %s", SDL_GetError());
+        LOGE("Could not initialize SDL: %s", SDL_GetError());
         return false;
     }