Problems with compiling BusyBox under Linux

A problem occurred when compiling the BusyBox:
SYNC.C: (. text.sync_main+0x78): Undefined reference to ' SYNCFS '
Collect2:ld returned 1 exit status
Make: * * * [busybox_unstripped] Error 1
Error is displayed under the sync.c file without defining something,
Our solution is to make the sync.c file not compile the connection and avoid its error
1: Locate the directory where the sync.c file is located

Find-name "SYNC.C"//In COREUTILS/SYNC.C
2: Open the directory of makefile or Kbuild find SYNC.O is controlled by WHO
lib-$ (config_sync) + = SYNC.O
3: Find the configuration entry for sync in Make menuconfig, and uncheck it

Problems with compiling BusyBox under Linux