fix build error use ld linker

src/observer/CMakeLists.txt

@@ -338,11 +338,15 @@ endif()
 target_link_libraries(observer
   PRIVATE
   ob_main
+  -Wl,--start-group
   oceanbase_static
-  -static-libgcc
-  -static-libstdc++
   ${link_malloc_hook}
   ${LGPL_DEPS}
+  oblib
+  easy
+  -Wl,--end-group
+  -static-libgcc
+  -static-libstdc++
   )
 execute_process(
   COMMAND sh -c "cd ${CMAKE_SOURCE_DIR} && git rev-parse HEAD"