Remove unused OS signal handlers in C

The idea is that we make just one OS signals handler on the C (CGO) side instead of Go and handle everything there from both, which is needed for proper termination process of multithreaded Libretro cores. But it leads to strange segfaults.

pkg/worker/emulator/libretro/nanoarch.c

@@ -3,8 +3,6 @@
 #include <stdbool.h>
 #include <stdarg.h>
 #include <stdio.h>
-//#include <stdlib.h>
-//#include <signal.h>
 
 int initialized = 0;
 
@@ -177,11 +175,6 @@ pthread_cond_t run_cv;
 pthread_mutex_t done_mutex;
 pthread_cond_t done_cv;
 
-// hack: go hangs with run_loop if SIGINT signal, so we handle it here
-//static void sig_handler(int _) {
-//    exit(0);
-//}
-
 void *run_loop(void *unused) {
     coreLog(RETRO_LOG_DEBUG, "UnLIBCo run loop start\n");
     pthread_mutex_lock(&done_mutex);