Fix source debugging issues (#776)

- fix data race issue between debug control thread and main thread
- fix possible memory leaks in breakpoints list
- fix memory uninitialized issues
- remove unused data structures
- add more checks when handling packet and args
- fix mini-loader issues
- fix config_common.cmake fast interp prompt issue

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

@@ -20,7 +20,7 @@ enum GDBStoppointType {
 };
 typedef struct WasmDebugPacket {
     unsigned char buf[PACKET_BUF_SIZE];
-    unsigned int end;
+    unsigned int size;
 } WasmDebugPacket;
 
 struct WASMDebugControlThread;