runtime: Reduce testing for fastlog2 implementation
runtime: Reduce testing for fastlog2 implementation

The current fastlog2 testing checks all 64M values in the domain of
interest, which is too much for platforms with no native floating point.

Reduce testing under testing.Short() to speed up builds for those platforms.

Related to #12620

Change-Id: Ie5dcd408724ba91c3b3fcf9ba0dddedb34706cd1
Reviewed-on: https://go-review.googlesource.com/15830
Reviewed-by: Keith Randall <8c99c3a9284e493be632950b84cd789d08ed3e9d@golang.org>
Reviewed-by: Joel Sing <55495163370d1a3b8fc0c7106120704aaf8de7f9@google.com>
Reviewed-by: Minux Ma <72d850dbd8858b791995463d8539b5a379577f28@golang.org>
Run-TryBot: Minux Ma <72d850dbd8858b791995463d8539b5a379577f28@golang.org>
TryBot-Result: Gobot Gobot <66cb808b70d30c07676d5e946fee83fd561249e5@golang.org>

Cofyc/go,deft-code/go,derekmarcotte/go,CAFxX/go,josharian/go,deft-code/go,cloudflare/go,Cofyc/go,odeke-em/go,Cofyc/go,nawawi/go,goodlang/good,vsekhar/elastic-go,kim-racktop/go,Cofyc/go,mwhudson/go,polyverse-security/go,Jordanzuo/go,linux-on-ibm-z/go,dterei/go,rachtsingh/gogojuice,Jordanzuo/go,cyberroadie/go,nawawi/go,vsekhar/elastic-go,fjballest/golang,vsekhar/elastic-go,josharian/go,gdey/go,linux-on-ibm-z/go,4ad/go,sndnvaps/go,sndnvaps/go,cloudflare/go,ganboing/go-esx,roth1002/go,sndnvaps/go,ganboing/go-esx,nawawi/go,vsekhar/elastic-go,polyverse-security/go,Jordanzuo/go,ImJasonH/go,binarycrusader/go,fjballest/golang,fjballest/golang,cyberroadie/go,roth1002/go,suncycheng/go,polyverse-security/go,ImJasonH/go,binarycrusader/go,Samurais/go,codestation/go,4ad/go,rachtsingh/gogojuice,rachtsingh/gogojuice,cloudflare/go,roth1002/go,ImJasonH/go,mwhudson/go,Jordanzuo/go,gdey/go,roth1002/go,kim-racktop/go,dterei/go,kim-racktop/go,golang/go,akutz/go,golang/go,suncycheng/go,derekmarcotte/go,goodlang/good,Samurais/go,codestation/go,fjballest/golang,sndnvaps/go,golang/go,miolini/go,polyverse-security/go,Endika/go,vanloswang/go,fjballest/golang,derekmarcotte/go,miolini/go,Endika/go,ganboing/go-esx,nawawi/go,vanloswang/go,4ad/go,dterei/go,mwhudson/go,suncycheng/go,miolini/go,polyverse-security/go,odeke-em/go,linux-on-ibm-z/go,dterei/go,kim-racktop/go,vanloswang/go,nawawi/go,golang/go,ganboing/go-esx,odeke-em/go,jacobsa/go,Samurais/go,sndnvaps/go,suncycheng/go,linux-on-ibm-z/go,theif519/go,mwhudson/go,theif519/go,gdey/go,akutz/go,vanloswang/go,Cofyc/go,suncycheng/go,4ad/go,rachtsingh/gogojuice,jacobsa/go,binarycrusader/go,malvira/go,Endika/go,dterei/go,theif519/go,binarycrusader/go,odeke-em/go,miolini/go,Jordanzuo/go,dterei/go,Endika/go,fjballest/golang,theif519/go,malvira/go,theif519/go,CAFxX/go,deft-code/go,binarycrusader/go,odeke-em/go,theif519/go,golang/go,ganboing/go-esx,momchil-velikov/go,CAFxX/go,CAFxX/go,vsekhar/elastic-go,jacobsa/go,4ad/go,derekmarcotte/go,CAFxX/go,sndnvaps/go,jacobsa/go,cloudflare/go,CAFxX/go,roth1002/go,Cofyc/go,derekmarcotte/go,ganboing/go-esx,goodlang/good,roth1002/go,ganboing/go-esx,malvira/go,malvira/go,momchil-velikov/go,nawawi/go,cyberroadie/go,Cofyc/go,sndnvaps/go,jacobsa/go,momchil-velikov/go,goodlang/good,polyverse-security/go,gdey/go,cyberroadie/go,CAFxX/go,fjballest/golang,mwhudson/go,suncycheng/go,cyberroadie/go,kim-racktop/go,polyverse-security/go,cyberroadie/go,mwhudson/go,Samurais/go,derekmarcotte/go,4ad/go,josharian/go,golang/go,polyverse-security/go,cyberroadie/go,rachtsingh/gogojuice,sndnvaps/go,Samurais/go,malvira/go,golang/go,cloudflare/go,cloudflare/go,malvira/go,cloudflare/go,miolini/go,theif519/go,akutz/go,jacobsa/go,akutz/go,ImJasonH/go,goodlang/good,codestation/go,deft-code/go,ImJasonH/go,goodlang/good,gdey/go,suncycheng/go,gdey/go,vanloswang/go,deft-code/go,cloudflare/go,goodlang/good,kim-racktop/go,4ad/go,binarycrusader/go,vanloswang/go,Jordanzuo/go,codestation/go,Cofyc/go,gdey/go,Jordanzuo/go,josharian/go,codestation/go,josharian/go,momchil-velikov/go,vanloswang/go,rachtsingh/gogojuice,josharian/go,Samurais/go,theif519/go,josharian/go,christopher-henderson/Go,vsekhar/elastic-go,momchil-velikov/go,akutz/go,jacobsa/go,ImJasonH/go,deft-code/go,gdey/go,roth1002/go,vsekhar/elastic-go,codestation/go,goodlang/good,ImJasonH/go,dterei/go,deft-code/go,Endika/go,linux-on-ibm-z/go,cyberroadie/go,4ad/go,binarycrusader/go,rachtsingh/gogojuice,codestation/go,fjballest/golang,deft-code/go,odeke-em/go,CAFxX/go,miolini/go,Samurais/go,odeke-em/go,Endika/go,dterei/go,akutz/go,malvira/go,akutz/go,linux-on-ibm-z/go,derekmarcotte/go,linux-on-ibm-z/go,odeke-em/go,nawawi/go,kim-racktop/go,ganboing/go-esx,nawawi/go,Samurais/go,akutz/go,mwhudson/go,josharian/go,momchil-velikov/go,momchil-velikov/go,rachtsingh/gogojuice,suncycheng/go,vsekhar/elastic-go,roth1002/go,binarycrusader/go,linux-on-ibm-z/go,Endika/go,golang/go,jacobsa/go,miolini/go,mwhudson/go,kim-racktop/go,Jordanzuo/go,miolini/go,malvira/go,vanloswang/go,derekmarcotte/go,codestation/go,Endika/go,ImJasonH/go,momchil-velikov/go