time: clarify Equal docs
time: clarify Equal docs

The docs used to imply that using == would compare Locations, but of
course it just compares Location pointers, which will have unpredictable
results depending on how the pointers are loaded.

Change-Id: I783c1309e476a9616a1c1c290eac713aba3b0b57
Reviewed-on: https://go-review.googlesource.com/32332
Reviewed-by: Brad Fitzpatrick <ae9783c0b0efc69cd85ab025ddd17aa44cdc4aa5@golang.org>

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