Implement source debugging for interpreter and AOT (#769)

Implement source debugging feature for classic interpreter and AOT:
- use `cmake -DWAMR_BUILD_DEBUG_INTERP=1` to enable interpreter debugging
- use `cmake -DWAMR_BUILD_DEBUG_AOT=1` to enable AOT debugging

See doc/source_debugging.md for more details.

core/iwasm/common/wasm_exec_env.h

@@ -20,6 +20,9 @@ struct WASMInterpFrame;
 
 #if WASM_ENABLE_THREAD_MGR != 0
 typedef struct WASMCluster WASMCluster;
+#if WASM_ENABLE_DEBUG_INTERP != 0
+typedef struct WASMCurrentEnvStatus WASMCurrentEnvStatus;
+#endif
 #endif
 
 #ifdef OS_ENABLE_HW_BOUND_CHECK
@@ -97,6 +100,10 @@ typedef struct WASMExecEnv {
     korp_cond wait_cond;
 #endif
 
+#if WASM_ENABLE_DEBUG_INTERP != 0
+    WASMCurrentEnvStatus *current_status;
+#endif
+
     /* attachment for native function */
     void *attachment;