i386 __sync_add_and_fetch_4 build error 

add 32bitsync label for some people who are suffering from __sync_add_and_fetch_4

these days,  many people experienced this build failure and adding CFLAGS=-march=i686 is not intuitive . because make 32bit overload user define CFLAGS. so 32bitsync will be useful for some people who wants to solve this problem.