Make _XOPEN_SOURCE definition agree with _POSIX_C_SOURCE for POSIX 2008 env
Make _XOPEN_SOURCE definition agree with _POSIX_C_SOURCE for POSIX 2008 env

Treat Solaris as POSIX 2001 as their check is not additive

Addresses https://github.com/facebook/libphenom/pull/47

rogerchina/libphenom,sakishum/libphenom,yangjin-unique/libphenom,sakishum/libphenom,zhakui/libphenom,yangjin-unique/libphenom,rogerchina/libphenom,zhenglaizhang/libphenom,sakishum/libphenom,zhenglaizhang/libphenom,yangjin-unique/libphenom,ChinaLongGanHu/libphenom,zhakui/libphenom,facebook/libphenom,yangjin-unique/libphenom,mhaberler/libphenom,seem-sky/libphenom,rogerchina/libphenom,dailypips/libphenom,ChinaLongGanHu/libphenom,facebook/libphenom,mhaberler/libphenom,dailypips/libphenom,zhenglaizhang/libphenom,facebook/libphenom,seem-sky/libphenom,mhaberler/libphenom,facebook/libphenom,seem-sky/libphenom,yangjin-unique/libphenom,zhakui/libphenom,ChinaLongGanHu/libphenom,mhaberler/libphenom,rogerchina/libphenom,dailypips/libphenom,sakishum/libphenom,sakishum/libphenom,zhenglaizhang/libphenom,zhakui/libphenom,dailypips/libphenom,rogerchina/libphenom,zhenglaizhang/libphenom,ChinaLongGanHu/libphenom,seem-sky/libphenom,zhakui/libphenom,ChinaLongGanHu/libphenom,mhaberler/libphenom,seem-sky/libphenom,dailypips/libphenom,facebook/libphenom