fix compile on gcc 12 (#218)

### What problem were solved in this pull request?

Issue Number: close #217 

Problem:
compile error on gcc 12

### What is changed and how it works?

### Other information

src/observer/net/buffered_writer.cpp

@@ -12,6 +12,7 @@ See the Mulan PSL v2 for more details. */
 // Created by Wangyunlai on 2023/06/16.
 //
 
+#include <sys/errno.h>
 #include <unistd.h>
 #include <algorithm>
 
@@ -131,4 +132,4 @@ RC BufferedWriter::flush_internal(int32_t size)
   }
 
   return rc;
-}
\ No newline at end of file
+}