added missing gflags include (for DEFINE_bool)
added missing gflags include (for DEFINE_bool)

wangg12/fbcunn,u20024804/fbcunn,facebook/fbcunn,Moodstocks/fbcunn,wangg12/fbcunn,facebook/fbcunn,yxdunc/fbcunn,Snazz2001/fbcunn,wangg12/fbcunn,ndronen/fbcunn,Snazz2001/fbcunn,yxdunc/fbcunn,RTBHOUSE/fbcunn,u20024804/fbcunn,RTBHOUSE/fbcunn,Moodstocks/fbcunn,facebook/fbcunn,linearregression/fbcunn,linearregression/fbcunn,ndronen/fbcunn,Snazz2001/fbcunn,linearregression/fbcunn,Moodstocks/fbcunn,yxdunc/fbcunn,u20024804/fbcunn,ndronen/fbcunn,RTBHOUSE/fbcunn