cmd/link: fix external linker argument for mips64
cmd/link: fix external linker argument for mips64

I overlooked it when rebasing CL 19803.

Change-Id: Ife9d6bcc6a772715d137af903c64bafac0cdb216
Reviewed-on: https://go-review.googlesource.com/22797
Reviewed-by: Minux Ma <72d850dbd8858b791995463d8539b5a379577f28@golang.org>

cloudflare/go,4ad/go,goodlang/good,josharian/go,suncycheng/go,polyverse-security/go,josharian/go,CAFxX/go,golang/go,Cofyc/go,derekmarcotte/go,momchil-velikov/go,polyverse-security/go,golang/go,christopher-henderson/Go,josharian/go,linux-on-ibm-z/go,josharian/go,ImJasonH/go,polyverse-security/go,cloudflare/go,theif519/go,linux-on-ibm-z/go,codestation/go,vsekhar/elastic-go,ganboing/go-esx,suncycheng/go,vsekhar/elastic-go,goodlang/good,Cofyc/go,Cofyc/go,suncycheng/go,Cofyc/go,ImJasonH/go,derekmarcotte/go,theif519/go,vsekhar/elastic-go,vsekhar/elastic-go,derekmarcotte/go,suncycheng/go,linux-on-ibm-z/go,ganboing/go-esx,momchil-velikov/go,goodlang/good,ganboing/go-esx,theif519/go,vsekhar/elastic-go,Cofyc/go,codestation/go,4ad/go,goodlang/good,akutz/go,josharian/go,linux-on-ibm-z/go,momchil-velikov/go,golang/go,nawawi/go,ganboing/go-esx,nawawi/go,nawawi/go,ImJasonH/go,nawawi/go,4ad/go,derekmarcotte/go,Cofyc/go,CAFxX/go,codestation/go,suncycheng/go,polyverse-security/go,nawawi/go,ImJasonH/go,josharian/go,momchil-velikov/go,derekmarcotte/go,akutz/go,goodlang/good,4ad/go,polyverse-security/go,suncycheng/go,ganboing/go-esx,vsekhar/elastic-go,momchil-velikov/go,polyverse-security/go,akutz/go,nawawi/go,ImJasonH/go,akutz/go,4ad/go,4ad/go,4ad/go,ImJasonH/go,suncycheng/go,nawawi/go,akutz/go,golang/go,cloudflare/go,josharian/go,codestation/go,golang/go,linux-on-ibm-z/go,ImJasonH/go,akutz/go,CAFxX/go,golang/go,polyverse-security/go,goodlang/good,4ad/go,cloudflare/go,Cofyc/go,goodlang/good,derekmarcotte/go,theif519/go,ganboing/go-esx,CAFxX/go,Cofyc/go,derekmarcotte/go,theif519/go,vsekhar/elastic-go,ganboing/go-esx,vsekhar/elastic-go,ImJasonH/go,cloudflare/go,codestation/go,linux-on-ibm-z/go,suncycheng/go,ganboing/go-esx,CAFxX/go,theif519/go,momchil-velikov/go,linux-on-ibm-z/go,derekmarcotte/go,akutz/go,linux-on-ibm-z/go,codestation/go,theif519/go,golang/go,golang/go,josharian/go,nawawi/go,CAFxX/go,cloudflare/go,goodlang/good,codestation/go,cloudflare/go,momchil-velikov/go,theif519/go,cloudflare/go,CAFxX/go,polyverse-security/go,CAFxX/go,akutz/go,codestation/go,momchil-velikov/go