Use offsetof() macro instead of expanded form.
Use offsetof() macro instead of expanded form.

Signed-off-by: Martin Sustrik <4dd6061be1198639e8b05ce4fd5ead7a0dcaa0f4@250bpm.com>

hyperfact/nanomsg,imp/nanomsg,wfxiang08/nanomsg,wirebirdlabs/featherweight-nanomsg,pch957/nanomsg,ttyangf/nanomsg,kaostao/nanomsg,pch957/nanomsg,modulexcite/nanomsg,TTimo/nanomsg,hyperfact/nanomsg,hyperfact/nanomsg,wirebirdlabs/featherweight-nanomsg,featherweight/ftw-kernel-nanomsg,modulexcite/nanomsg,imp/nanomsg,JackDunaway/featherweight-nanomsg,wirebirdlabs/featherweight-nanomsg,tempbottle/nanomsg,imp/nanomsg,zerotacg/nanomsg,pakozm/nanomsg,snikulov/nanomsg,kaostao/nanomsg,potatogim/nanomsg,pch957/nanomsg,wfxiang08/nanomsg,gdamore/mamomsg,zerotacg/nanomsg,cosin2008/nanomsg.NET,reqshark/nanomsg,simplestbest/nanomsg,ttyangf/nanomsg,thisco-de/nanomsg,nirs/nanomsg,kaostao/nanomsg,smithed/nanomsg,nirs/nanomsg,featherweight/ftw-kernel-nanomsg,smithed/nanomsg,potatogim/nanomsg,krafczyk/nanomsg,ttyangf/nanomsg,simplestbest/nanomsg,krafczyk/nanomsg,yan97ao/nanomsg,pakozm/nanomsg,TTimo/nanomsg,nirs/nanomsg,zerotacg/nanomsg,ttyangf/nanomsg,yan97ao/nanomsg,JackDunaway/featherweight-nanomsg,kaostao/nanomsg,linearregression/nanomsg,cosin2008/nanomsg.NET,linearregression/nanomsg,yan97ao/nanomsg,TTimo/nanomsg,wfxiang08/nanomsg,potatogim/nanomsg,thisco-de/nanomsg,JackDunaway/featherweight-nanomsg,cosin2008/nanomsg.NET,smithed/nanomsg,linearregression/nanomsg,reqshark/nanomsg,smithed/nanomsg,tempbottle/nanomsg,gdamore/mamomsg,snikulov/nanomsg,tempbottle/nanomsg,simplestbest/nanomsg,pakozm/nanomsg,reqshark/nanomsg,modulexcite/nanomsg,krafczyk/nanomsg,gdamore/mamomsg,TTimo/nanomsg