Timeout error (#1173)

* Implement timeout state and new error for such case

* Adjust test_i386_loop sample

* Adjust test_i386_loop test

include/unicorn/unicorn.h

@@ -163,7 +163,8 @@ typedef enum uc_err {
     UC_ERR_FETCH_UNALIGNED,  // Unaligned fetch
     UC_ERR_HOOK_EXIST,  // hook for this event already existed
     UC_ERR_RESOURCE,    // Insufficient resource: uc_emu_start()
-    UC_ERR_EXCEPTION // Unhandled CPU exception
+    UC_ERR_EXCEPTION, // Unhandled CPU exception
+    UC_ERR_TIMEOUT // Emulation timed out
 } uc_err;