std: several minor cleanups wrt codereview.. see extended comments
std: several minor cleanups wrt codereview.. see extended comments

* there are a few places where I was experimenting w/ using `alt` in places
where `if`/`else` would've sufficed. don't drink the koolaid!
* I had an unneeded `else` structure (the `if` branch that preceeded
concluded with a `fail` statement.. I added the `fail` later in the dev
cycle for this branch, so I forgot to remove the `else` after doing so)
* consistent wrt `prop_name: value` vs. `prop_name : value` in record decl
and initialization
* change an `alt` exp on an `ip_addr` to actually be exhaustive,
instead of using a catch-all clause

zaeleus/rust,erickt/rust,dwillmer/rust,quornian/rust,j16r/rust,shepmaster/rand,nwin/rust,philyoon/rust,bombless/rust,AerialX/rust,reem/rust,michaelballantyne/rust-gpu,ebfull/rand,aturon/rust,emk/rust,defuz/rust,krzysz00/rust,cllns/rust,jbclements/rust,GrahamDennis/rand,KokaKiwi/rust,emk/rust,mahkoh/rust,ruud-v-a/rust,robertg/rust,sae-bom/rust,nham/rust,omasanori/rust,mvdnes/rust,pshc/rust,AerialX/rust-rt-minimal,mihneadb/rust,P1start/rust,mahkoh/rust,ebfull/rust,servo/rust,ruud-v-a/rust,kmcallister/rust,mdinger/rust,retep998/rand,stepancheg/rust-ide-rust,SiegeLord/rust,mahkoh/rust,ejjeong/rust,dwillmer/rust,aturon/rust,0x73/rust,philyoon/rust,richo/rust,ruud-v-a/rust,robertg/rust,barosl/rust,nham/rust,AerialX/rust,carols10cents/rust,GBGamer/rust,erickt/rust,andars/rust,barosl/rust,nham/rust,sae-bom/rust,andars/rust,l0kod/rust,omasanori/rust,l0kod/rust,zubron/rust,jroesch/rust,XMPPwocky/rust,rprichard/rust,erickt/rust,pczarn/rust,mahkoh/rust,kmcallister/rust,stepancheg/rust-ide-rust,aepsil0n/rust,avdi/rust,zubron/rust,stepancheg/rust-ide-rust,stepancheg/rust-ide-rust,vhbit/rust,j16r/rust,mihneadb/rust,jroesch/rust,pczarn/rust,TheNeikos/rust,aepsil0n/rust,mvdnes/rust,reem/rust,kwantam/rust,AerialX/rust-rt-minimal,aturon/rust,dwillmer/rust,mvdnes/rust,pelmers/rust,jashank/rust,aneeshusa/rust,carols10cents/rust,aneeshusa/rust,aepsil0n/rust,aidancully/rust,rohitjoshi/rust,pshc/rust,AerialX/rust,dwillmer/rust,KokaKiwi/rust,victorvde/rust,XMPPwocky/rust,reem/rust,Ryman/rust,aepsil0n/rust,LeoTestard/rust,gifnksm/rust,rprichard/rust,jbclements/rust,gifnksm/rust,richo/rust,seanrivera/rust,sarojaba/rust-doc-korean,P1start/rust,mitsuhiko/rust,zachwick/rust,omasanori/rust,dwillmer/rust,pshc/rust,cllns/rust,kmcallister/rust,GBGamer/rust,robertg/rust,untitaker/rust,seanrivera/rust,zubron/rust,TheNeikos/rust,mvdnes/rust,stepancheg/rust-ide-rust,kmcallister/rust,fabricedesre/rust,vhbit/rust,aturon/rust,servo/rust,LeoTestard/rust,michaelballantyne/rust-gpu,miniupnp/rust,sarojaba/rust-doc-korean,rprichard/rust,nham/rust,bhickey/rand,SiegeLord/rust,carols10cents/rust,nwin/rust,kimroen/rust,ejjeong/rust,fabricedesre/rust,andars/rust,Ryman/rust,jbclements/rust,LeoTestard/rust,kwantam/rust,nwin/rust,graydon/rust,jroesch/rust,LeoTestard/rust,aepsil0n/rust,carols10cents/rust,rohitjoshi/rust,miniupnp/rust,kmcallister/rust,robertg/rust,kwantam/rust,vhbit/rust,jbclements/rust,bombless/rust,rohitjoshi/rust,hauleth/rust,ktossell/rust,TheNeikos/rust,kimroen/rust,servo/rust,pythonesque/rust,pelmers/rust,stepancheg/rust-ide-rust,cllns/rust,l0kod/rust,bombless/rust,omasanori/rust,pshc/rust,l0kod/rust,kimroen/rust,pelmers/rust,KokaKiwi/rust,quornian/rust,ebfull/rust,philyoon/rust,mihneadb/rust,miniupnp/rust,mitsuhiko/rust,kimroen/rust,servo/rust,zaeleus/rust,andars/rust,jbclements/rust,jbclements/rust,pelmers/rust,omasanori/rust,sae-bom/rust,mitsuhiko/rust,quornian/rust,bombless/rust,victorvde/rust,l0kod/rust,sarojaba/rust-doc-korean,ebfull/rust,gifnksm/rust,mihneadb/rust,kmcallister/rust,ruud-v-a/rust,SiegeLord/rust,bombless/rust-docs-chinese,aidancully/rust,krzysz00/rust,P1start/rust,graydon/rust,zachwick/rust,nwin/rust,pythonesque/rust,0x73/rust,kwantam/rust,ktossell/rust,mvdnes/rust,ktossell/rust,0x73/rust,barosl/rust,pythonesque/rust,P1start/rust,l0kod/rust,robertg/rust,kimroen/rust,rprichard/rust,graydon/rust,richo/rust,victorvde/rust,fabricedesre/rust,Ryman/rust,michaelballantyne/rust-gpu,dinfuehr/rust,jbclements/rust,ejjeong/rust,sae-bom/rust,ruud-v-a/rust,ebfull/rust,michaelballantyne/rust-gpu,nham/rust,mihneadb/rust,nham/rust,AerialX/rust-rt-minimal,reem/rust,rohitjoshi/rust,waynenilsen/rand,0x73/rust,aneeshusa/rust,kwantam/rust,pythonesque/rust,aturon/rust,pczarn/rust,P1start/rust,pelmers/rust,dinfuehr/rust,zachwick/rust,AerialX/rust-rt-minimal,aturon/rust,GBGamer/rust,GBGamer/rust,kimroen/rust,krzysz00/rust,ruud-v-a/rust,ejjeong/rust,SiegeLord/rust,ktossell/rust,reem/rust,defuz/rust,KokaKiwi/rust,jroesch/rust,aepsil0n/rust,seanrivera/rust,mdinger/rust,AerialX/rust,aneeshusa/rust,SiegeLord/rust,barosl/rust,dinfuehr/rust,pczarn/rust,quornian/rust,AerialX/rust,AerialX/rust-rt-minimal,dinfuehr/rust,Ryman/rust,philyoon/rust,emk/rust,aidancully/rust,mihneadb/rust,GBGamer/rust,mdinger/rust,untitaker/rust,victorvde/rust,TheNeikos/rust,bluss/rand,miniupnp/rust,hauleth/rust,j16r/rust,andars/rust,j16r/rust,pythonesque/rust,robertg/rust,jroesch/rust,erickt/rust,barosl/rust,XMPPwocky/rust,michaelballantyne/rust-gpu,pczarn/rust,AerialX/rust-rt-minimal,mahkoh/rust,l0kod/rust,mvdnes/rust,seanrivera/rust,dinfuehr/rust,graydon/rust,nham/rust,kimroen/rust,zaeleus/rust,untitaker/rust,miniupnp/rust,KokaKiwi/rust,huonw/rand,defuz/rust,GBGamer/rust,jroesch/rust,arthurprs/rand,avdi/rust,l0kod/rust,aneeshusa/rust,pythonesque/rust,pshc/rust,0x73/rust,cllns/rust,TheNeikos/rust,emk/rust,carols10cents/rust,servo/rust,fabricedesre/rust,avdi/rust,GBGamer/rust,nwin/rust,pshc/rust,0x73/rust,gifnksm/rust,kwantam/rust,GBGamer/rust,bombless/rust,zubron/rust,rohitjoshi/rust,krzysz00/rust,rprichard/rust,quornian/rust,krzysz00/rust,aidancully/rust,vhbit/rust,pshc/rust,zubron/rust,nwin/rust,aidancully/rust,servo/rust,Ryman/rust,nwin/rust,avdi/rust,seanrivera/rust,P1start/rust,pythonesque/rust,zaeleus/rust,zaeleus/rust,richo/rust,mitsuhiko/rust,LeoTestard/rust,ktossell/rust,kmcallister/rust,Ryman/rust,hauleth/rust,erickt/rust,achanda/rand,j16r/rust,sarojaba/rust-doc-korean,dwillmer/rust,zachwick/rust,emk/rust,j16r/rust,jashank/rust,rprichard/rust,philyoon/rust,P1start/rust,barosl/rust,mitsuhiko/rust,fabricedesre/rust,XMPPwocky/rust,carols10cents/rust,zaeleus/rust,KokaKiwi/rust,emk/rust,vhbit/rust,SiegeLord/rust,mdinger/rust,zubron/rust,hauleth/rust,miniupnp/rust,aneeshusa/rust,gifnksm/rust,vhbit/rust,richo/rust,cllns/rust,jashank/rust,stepancheg/rust-ide-rust,erickt/rust,quornian/rust,LeoTestard/rust,krzysz00/rust,jashank/rust,zubron/rust,zubron/rust,quornian/rust,andars/rust,sarojaba/rust-doc-korean,zachwick/rust,0x73/rust,sae-bom/rust,jashank/rust,seanrivera/rust,miniupnp/rust,richo/rust,mdinger/rust,ebfull/rust,aturon/rust,mitsuhiko/rust,jashank/rust,victorvde/rust,dwillmer/rust,ktossell/rust,TheNeikos/rust,ejjeong/rust,avdi/rust,jashank/rust,defuz/rust,erickt/rust,cllns/rust,nwin/rust,graydon/rust,pczarn/rust,vhbit/rust,victorvde/rust,XMPPwocky/rust,pshc/rust,aidancully/rust,dwillmer/rust,Ryman/rust,sarojaba/rust-doc-korean,miniupnp/rust,michaelballantyne/rust-gpu,ktossell/rust,SiegeLord/rust,graydon/rust,sae-bom/rust,rohitjoshi/rust,fabricedesre/rust,omasanori/rust,bombless/rust,mahkoh/rust,jashank/rust,philyoon/rust,AerialX/rust,pczarn/rust,jroesch/rust,jroesch/rust,hauleth/rust,LeoTestard/rust,vhbit/rust,jbclements/rust,pelmers/rust,untitaker/rust,avdi/rust,gifnksm/rust,untitaker/rust,j16r/rust,untitaker/rust,ejjeong/rust,defuz/rust,dinfuehr/rust,reem/rust,emk/rust,mitsuhiko/rust,XMPPwocky/rust,sarojaba/rust-doc-korean,hauleth/rust,barosl/rust,jbclements/rust,ebfull/rust,fabricedesre/rust,defuz/rust,servo/rust,mdinger/rust,michaelballantyne/rust-gpu,zachwick/rust