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/aot/aot_runtime.h

@@ -254,6 +254,10 @@ typedef struct AOTModule {
     WASIArguments wasi_args;
     bool is_wasi_module;
 #endif
+#if WASM_ENABLE_DEBUG_AOT != 0
+    void *elf_hdr;
+    uint32 elf_size;
+#endif
 } AOTModule;
 
 typedef union {