Enable the +v7 feature on Android by default
Enable the +v7 feature on Android by default

With the recently added double word CAS functionality on 32-bit ARM (enabled via
a 64-bit atomic instruction in LLVM IR), without some extra features enabled
LLVM lowers code to function calls which emulate atomic instructions. With the
v7 feature enabled, proper 64-bit CAS instructions are used on 32-bit arm.

I've been told that v7 for arm is what we should have been doing anyway. This is
overridable by providing some other non-empty feature string.

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