Enable emitting custom name section to aot file (#794)

Enable emitting custom name section to aot file when adding
`--enable-dump-call-stack` or `--enable-dump-call-stack` to
wamrc and there is custom name section in wasm file, which
can be generated by wasi-sdk/emcc "-g" option. So aot runtime
can also get the function name from the custom name section
instead of export section,  to which developer should use
`--export-all` for wasi-sdk/emcc to generate export function
names.

core/iwasm/interpreter/wasm.h

@@ -418,6 +418,11 @@ struct WASMModule {
     uint64 load_size;
     uint64 buf_code_size;
 #endif
+
+#if WASM_ENABLE_CUSTOM_NAME_SECTION != 0
+    const uint8 *name_section_buf;
+    const uint8 *name_section_buf_end;
+#endif
 };
 
 typedef struct BlockType {