debug-engine: fix a few type mismatches (#4189)

- use strict prototypes complained by GCC `-Wstrict-prototypes`
- use `int*` instead of `int32*`

Note: on some targets, int32_t is a long.
for example, GCC shipped with the recent ESP-IDF has such a
configuration.

- https://github.com/apache/nuttx/issues/15755#issuecomment-2635652808
- https://github.com/apache/nuttx/pull/16022
- https://docs.espressif.com/projects/esp-idf/en/stable/esp32/migration-guides/release-5.x/5.0/gcc.html#espressif-toolchain-changes

core/iwasm/libraries/debug-engine/handler.h

@@ -9,10 +9,10 @@
 #include "gdbserver.h"
 
 int
-wasm_debug_handler_init();
+wasm_debug_handler_init(void);
 
 void
-wasm_debug_handler_deinit();
+wasm_debug_handler_deinit(void);
 
 void
 handle_interrupt(WASMGDBServer *server);