sync: Update the arc module
sync: Update the arc module

This removes the now-outdated MutexArc and RWArc types. These are superseded by
Arc<Mutex<T>> and Arc<RWLock<T>>. The only remaining arc is the one true Arc.
Additionally, the arc now has weak pointers implemented for it to assist in
breaking cycles.

This commit brings the arc api up to parity with the sibling Rc api, making them
nearly interchangeable for inter and intra task communication.

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