[dev.ssa] cmd/compile: handle OLITERAL nil expressions
[dev.ssa] cmd/compile: handle OLITERAL nil expressions

Change-Id: I02b8fb277b486eaf0916ddcd8f28c062d4022d4b
Reviewed-on: https://go-review.googlesource.com/12150
Reviewed-by: Keith Randall <8c99c3a9284e493be632950b84cd789d08ed3e9d@golang.org>

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