auto merge of #10508 : chris-morgan/rust/tags-improvements, r=cmr
auto merge of #10508 : chris-morgan/rust/tags-improvements, r=cmr

Largely, this is just being more specific about where tags get searched
for to remove external dependencies like src/llvm, which reduces the
number of tags *enormously* and significantly increases the usefulness
of the tags file as it is then focusing on 240K lines of Rust code
and 4.5K of C++ rather than just shy of 1M lines of C++ code (mostly
from LLVM) and another 100K lines of Rust tests and a diverse collection
of other languages.

src/rustllvm/RustWrapper.cpp and src/rustllvm/PassWrapper.cpp are
getting tags made, but I'm not sure if that's desirable or not. At
worst, it's not a significant wrong.

A future, desirable step is producing tags for just libstd and libextra
for the use of people using Rust-the-language rather than working on
Rust itself.

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