Remove definition of __STDC_FORMAT_MACROS
Remove definition of __STDC_FORMAT_MACROS

Summary: This is no longer used.

Test Plan: Redefinition warning goes away in HHVM build.

Reviewed By: @pavlo-fb

Differential Revision: D1850889
reddit/mcrouter,reddit/mcrouter,tempbottle/mcrouter,seem-sky/mcrouter,yqzhang/mcrouter,reddit/mcrouter,tempbottle/mcrouter,synecdoche/mcrouter,synecdoche/mcrouter,apinski-cavium/mcrouter,nvaller/mcrouter,evertrue/mcrouter,yqzhang/mcrouter,leitao/mcrouter,is00hcw/mcrouter,zhlong73/mcrouter,yqzhang/mcrouter,seem-sky/mcrouter,glensc/mcrouter,easyfmxu/mcrouter,seem-sky/mcrouter,nvaller/mcrouter,glensc/mcrouter,reddit/mcrouter,evertrue/mcrouter,is00hcw/mcrouter,nvaller/mcrouter,nvaller/mcrouter,apinski-cavium/mcrouter,yqzhang/mcrouter,leitao/mcrouter,is00hcw/mcrouter,synecdoche/mcrouter,easyfmxu/mcrouter,glensc/mcrouter,apinski-cavium/mcrouter,facebook/mcrouter,facebook/mcrouter,is00hcw/mcrouter,zhlong73/mcrouter,tempbottle/mcrouter,glensc/mcrouter,zhlong73/mcrouter,easyfmxu/mcrouter,tempbottle/mcrouter,facebook/mcrouter,synecdoche/mcrouter,leitao/mcrouter,facebook/mcrouter,apinski-cavium/mcrouter,evertrue/mcrouter,evertrue/mcrouter,leitao/mcrouter,easyfmxu/mcrouter,zhlong73/mcrouter,seem-sky/mcrouter