Add `--pretty everybody_loops` option.
Add `--pretty everybody_loops` option.

This prints out a transformed version of the input source code where
every function body is replaced with `loop { }`.

All such bodies are (1.) trivial and (2.) guaranteed to pass the
type-checker in a valid compiler; therefore they make very nice input
to start with when narrowing down a bug exposed by a large test input
(such as librustc itself).

defuz/rust,ruud-v-a/rust,zachwick/rust,dinfuehr/rust,kimroen/rust,kimroen/rust,zaeleus/rust,untitaker/rust,XMPPwocky/rust,philyoon/rust,krzysz00/rust,aneeshusa/rust,robertg/rust,KokaKiwi/rust,defuz/rust,l0kod/rust,hauleth/rust,zaeleus/rust,jroesch/rust,aidancully/rust,gifnksm/rust,defuz/rust,mahkoh/rust,GBGamer/rust,richo/rust,dinfuehr/rust,nwin/rust,nwin/rust,kimroen/rust,pelmers/rust,sae-bom/rust,mihneadb/rust,TheNeikos/rust,AerialX/rust-rt-minimal,avdi/rust,aepsil0n/rust,sae-bom/rust,zaeleus/rust,ktossell/rust,victorvde/rust,GBGamer/rust,pshc/rust,carols10cents/rust,AerialX/rust-rt-minimal,jroesch/rust,carols10cents/rust,mahkoh/rust,defuz/rust,philyoon/rust,ejjeong/rust,andars/rust,reem/rust,AerialX/rust,ruud-v-a/rust,omasanori/rust,zachwick/rust,pshc/rust,zubron/rust,zachwick/rust,dwillmer/rust,ktossell/rust,nwin/rust,dwillmer/rust,krzysz00/rust,ejjeong/rust,zubron/rust,ebfull/rust,carols10cents/rust,avdi/rust,l0kod/rust,kwantam/rust,pelmers/rust,dwillmer/rust,zubron/rust,carols10cents/rust,AerialX/rust,zubron/rust,mihneadb/rust,vhbit/rust,zachwick/rust,graydon/rust,mahkoh/rust,ejjeong/rust,XMPPwocky/rust,pshc/rust,nwin/rust,carols10cents/rust,ktossell/rust,graydon/rust,KokaKiwi/rust,mihneadb/rust,TheNeikos/rust,ebfull/rust,richo/rust,gifnksm/rust,pshc/rust,sae-bom/rust,mahkoh/rust,TheNeikos/rust,mvdnes/rust,ktossell/rust,aepsil0n/rust,victorvde/rust,avdi/rust,seanrivera/rust,bombless/rust-docs-chinese,defuz/rust,krzysz00/rust,krzysz00/rust,zaeleus/rust,andars/rust,philyoon/rust,rprichard/rust,mvdnes/rust,jashank/rust,graydon/rust,richo/rust,AerialX/rust,pelmers/rust,aidancully/rust,ebfull/rust,kimroen/rust,richo/rust,philyoon/rust,KokaKiwi/rust,mahkoh/rust,aidancully/rust,cllns/rust,mihneadb/rust,kwantam/rust,hauleth/rust,ktossell/rust,defuz/rust,XMPPwocky/rust,aneeshusa/rust,l0kod/rust,kimroen/rust,omasanori/rust,mdinger/rust,pshc/rust,untitaker/rust,andars/rust,miniupnp/rust,XMPPwocky/rust,rprichard/rust,miniupnp/rust,gifnksm/rust,nwin/rust,sae-bom/rust,zubron/rust,kwantam/rust,sae-bom/rust,l0kod/rust,seanrivera/rust,ruud-v-a/rust,pelmers/rust,pelmers/rust,mdinger/rust,jashank/rust,bombless/rust,dinfuehr/rust,nwin/rust,omasanori/rust,rohitjoshi/rust,rprichard/rust,dwillmer/rust,philyoon/rust,ktossell/rust,dwillmer/rust,avdi/rust,mihneadb/rust,GBGamer/rust,cllns/rust,gifnksm/rust,cllns/rust,GBGamer/rust,hauleth/rust,untitaker/rust,XMPPwocky/rust,krzysz00/rust,aidancully/rust,mahkoh/rust,aepsil0n/rust,ebfull/rust,jashank/rust,AerialX/rust,AerialX/rust-rt-minimal,l0kod/rust,AerialX/rust-rt-minimal,seanrivera/rust,aepsil0n/rust,robertg/rust,GBGamer/rust,omasanori/rust,hauleth/rust,zaeleus/rust,gifnksm/rust,rohitjoshi/rust,ruud-v-a/rust,aepsil0n/rust,rohitjoshi/rust,miniupnp/rust,ejjeong/rust,rohitjoshi/rust,aidancully/rust,vhbit/rust,KokaKiwi/rust,andars/rust,bombless/rust,mdinger/rust,andars/rust,victorvde/rust,rprichard/rust,AerialX/rust,bombless/rust,jashank/rust,l0kod/rust,TheNeikos/rust,jroesch/rust,vhbit/rust,mihneadb/rust,mvdnes/rust,untitaker/rust,miniupnp/rust,miniupnp/rust,victorvde/rust,bombless/rust,victorvde/rust,rohitjoshi/rust,ruud-v-a/rust,kimroen/rust,jroesch/rust,AerialX/rust,TheNeikos/rust,pshc/rust,KokaKiwi/rust,GBGamer/rust,aneeshusa/rust,vhbit/rust,nwin/rust,reem/rust,jroesch/rust,dwillmer/rust,mvdnes/rust,jashank/rust,zachwick/rust,vhbit/rust,untitaker/rust,kwantam/rust,TheNeikos/rust,hauleth/rust,andars/rust,ebfull/rust,GBGamer/rust,victorvde/rust,richo/rust,robertg/rust,ktossell/rust,miniupnp/rust,AerialX/rust-rt-minimal,mdinger/rust,avdi/rust,rprichard/rust,jashank/rust,aepsil0n/rust,dinfuehr/rust,zubron/rust,jroesch/rust,pshc/rust,nwin/rust,reem/rust,GBGamer/rust,krzysz00/rust,aneeshusa/rust,seanrivera/rust,philyoon/rust,robertg/rust,jroesch/rust,omasanori/rust,vhbit/rust,mvdnes/rust,dwillmer/rust,avdi/rust,zubron/rust,omasanori/rust,ruud-v-a/rust,rprichard/rust,hauleth/rust,bombless/rust,aneeshusa/rust,miniupnp/rust,graydon/rust,KokaKiwi/rust,zaeleus/rust,AerialX/rust-rt-minimal,mvdnes/rust,zachwick/rust,ebfull/rust,cllns/rust,ejjeong/rust,dwillmer/rust,l0kod/rust,reem/rust,dinfuehr/rust,aneeshusa/rust,miniupnp/rust,carols10cents/rust,robertg/rust,untitaker/rust,cllns/rust,robertg/rust,kimroen/rust,graydon/rust,reem/rust,kwantam/rust,bombless/rust,XMPPwocky/rust,richo/rust,jroesch/rust,rohitjoshi/rust,dinfuehr/rust,sae-bom/rust,seanrivera/rust,vhbit/rust,cllns/rust,mdinger/rust,vhbit/rust,gifnksm/rust,seanrivera/rust,graydon/rust,jashank/rust,reem/rust,pshc/rust,l0kod/rust,zubron/rust,aidancully/rust,jashank/rust,mdinger/rust,ejjeong/rust,kwantam/rust,pelmers/rust