cmd/compile: simplify isglobal
cmd/compile: simplify isglobal

Passes toolstash -cmp.

Change-Id: I16ec0c11096bf4c020cf41392effeb67436f32ba
Reviewed-on: https://go-review.googlesource.com/26750
Run-TryBot: Josh Bleecher Snyder <cdc248cc4d32e4fbfe04e45228163bcecd48a0b9@gmail.com>
TryBot-Result: Gobot Gobot <66cb808b70d30c07676d5e946fee83fd561249e5@golang.org>
Reviewed-by: Brad Fitzpatrick <ae9783c0b0efc69cd85ab025ddd17aa44cdc4aa5@golang.org>

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