Adding sys/socket.h constants for iOS/Mac, particularly for SO_SOCKET options.
Adding sys/socket.h constants for iOS/Mac, particularly for SO_SOCKET options.

This is probably more broadly applicable than these two platforms
(since it's part of the bsd4.4 standard) but that's outside my problem domain today.
If this goes well, I may submit Linux/64 support in a separate PR.

Reviewers should take a look at http://www.opensource.apple.com/source/xnu/xnu-792.17.14/bsd/sys/socket.h?txt
which defines constants for OSX.  iOS uses the same header.

I release this patch under the MIT license.

pshc/rust,ejjeong/rust,dwillmer/rust,XMPPwocky/rust,mvdnes/rust,zachwick/rust,aidancully/rust,carols10cents/rust,zubron/rust,gifnksm/rust,zubron/rust,seanrivera/rust,avdi/rust,andars/rust,ejjeong/rust,reem/rust,dwillmer/rust,zubron/rust,l0kod/rust,vhbit/rust,ruud-v-a/rust,ebfull/rust,avdi/rust,avdi/rust,ruud-v-a/rust,rohitjoshi/rust,XMPPwocky/rust,gifnksm/rust,dwillmer/rust,omasanori/rust,robertg/rust,l0kod/rust,nwin/rust,XMPPwocky/rust,philyoon/rust,nwin/rust,aidancully/rust,KokaKiwi/rust,XMPPwocky/rust,omasanori/rust,sae-bom/rust,pshc/rust,kwantam/rust,zachwick/rust,mihneadb/rust,nwin/rust,TheNeikos/rust,ruud-v-a/rust,ruud-v-a/rust,krzysz00/rust,mvdnes/rust,omasanori/rust,mdinger/rust,nwin/rust,reem/rust,philyoon/rust,jroesch/rust,seanrivera/rust,zachwick/rust,philyoon/rust,reem/rust,aidancully/rust,carols10cents/rust,graydon/rust,cllns/rust,zaeleus/rust,sae-bom/rust,victorvde/rust,kwantam/rust,zachwick/rust,rohitjoshi/rust,ebfull/rust,ebfull/rust,dwillmer/rust,jashank/rust,TheNeikos/rust,robertg/rust,GBGamer/rust,jashank/rust,andars/rust,pshc/rust,vhbit/rust,aneeshusa/rust,aepsil0n/rust,mvdnes/rust,andars/rust,pelmers/rust,zubron/rust,ejjeong/rust,GBGamer/rust,seanrivera/rust,seanrivera/rust,carols10cents/rust,pshc/rust,vhbit/rust,zachwick/rust,sae-bom/rust,philyoon/rust,l0kod/rust,pelmers/rust,aepsil0n/rust,KokaKiwi/rust,gifnksm/rust,dwillmer/rust,avdi/rust,mdinger/rust,jashank/rust,nwin/rust,avdi/rust,zachwick/rust,aidancully/rust,robertg/rust,zaeleus/rust,krzysz00/rust,ejjeong/rust,carols10cents/rust,reem/rust,omasanori/rust,aneeshusa/rust,aepsil0n/rust,pshc/rust,vhbit/rust,mvdnes/rust,nwin/rust,reem/rust,graydon/rust,rohitjoshi/rust,carols10cents/rust,seanrivera/rust,mdinger/rust,andars/rust,XMPPwocky/rust,jroesch/rust,carols10cents/rust,avdi/rust,mihneadb/rust,mihneadb/rust,dwillmer/rust,jroesch/rust,cllns/rust,nwin/rust,zaeleus/rust,miniupnp/rust,mdinger/rust,kwantam/rust,cllns/rust,mihneadb/rust,victorvde/rust,mihneadb/rust,robertg/rust,TheNeikos/rust,zubron/rust,miniupnp/rust,jashank/rust,miniupnp/rust,kwantam/rust,jashank/rust,ebfull/rust,mvdnes/rust,victorvde/rust,kwantam/rust,ebfull/rust,jashank/rust,GBGamer/rust,aneeshusa/rust,GBGamer/rust,mihneadb/rust,krzysz00/rust,l0kod/rust,miniupnp/rust,graydon/rust,GBGamer/rust,rohitjoshi/rust,zaeleus/rust,jroesch/rust,aidancully/rust,jroesch/rust,zaeleus/rust,aneeshusa/rust,ruud-v-a/rust,omasanori/rust,gifnksm/rust,vhbit/rust,zubron/rust,pelmers/rust,TheNeikos/rust,gifnksm/rust,GBGamer/rust,KokaKiwi/rust,sae-bom/rust,kwantam/rust,GBGamer/rust,miniupnp/rust,aidancully/rust,victorvde/rust,vhbit/rust,GBGamer/rust,aneeshusa/rust,philyoon/rust,jroesch/rust,KokaKiwi/rust,ebfull/rust,andars/rust,robertg/rust,graydon/rust,gifnksm/rust,rohitjoshi/rust,jroesch/rust,pshc/rust,omasanori/rust,TheNeikos/rust,KokaKiwi/rust,rohitjoshi/rust,graydon/rust,vhbit/rust,pelmers/rust,aepsil0n/rust,aneeshusa/rust,robertg/rust,sae-bom/rust,jashank/rust,victorvde/rust,mvdnes/rust,cllns/rust,krzysz00/rust,seanrivera/rust,miniupnp/rust,l0kod/rust,cllns/rust,andars/rust,l0kod/rust,victorvde/rust,aepsil0n/rust,dwillmer/rust,XMPPwocky/rust,zubron/rust,krzysz00/rust,dwillmer/rust,l0kod/rust,zubron/rust,zaeleus/rust,ruud-v-a/rust,jroesch/rust,l0kod/rust,graydon/rust,miniupnp/rust,sae-bom/rust,mdinger/rust,cllns/rust,KokaKiwi/rust,ejjeong/rust,ejjeong/rust,mdinger/rust,pshc/rust,philyoon/rust,pshc/rust,pelmers/rust,aepsil0n/rust,pelmers/rust,TheNeikos/rust,reem/rust,krzysz00/rust,jashank/rust,vhbit/rust,nwin/rust,miniupnp/rust