go/ssa/interp: abort long-running test when testing.Short() is set
go/ssa/interp: abort long-running test when testing.Short() is set

This should help on slower machines.

For golang/go#11811.

Change-Id: Ibb5d5bf0f6cedcda6437ef0ee3fc1f4ba89dab90
Reviewed-on: https://go-review.googlesource.com/13009
Reviewed-by: Ian Lance Taylor <87e9c6d529889242b7e184afb632328636553ab4@golang.org>

syreclabs/go-tools,jdhenke/tools,golang/tools,matryer/tools,cw2018/tools,syreclabs/go-tools,syreclabs/go-tools,jdhenke/tools,syreclabs/go-tools,runcom/tools,springning/tools,springning/tools,matryer/tools,argandas/tools,golang/tools,argandas/tools,josharian/tools,springning/tools,nicot/tools,cw2018/tools,magiccao/tools,cmars/tools,jdhenke/tools,matryer/tools,glasser/golang-tools,nicot/tools,glasser/golang-tools,matryer/tools,golang/tools,cmars/tools,cmars/tools,cw2018/tools,springning/tools,runcom/tools,argandas/tools,magiccao/tools,argandas/tools,runcom/tools,cw2018/tools,glasser/golang-tools,syreclabs/go-tools,runcom/tools,cmars/tools,josharian/tools,josharian/tools,nicot/tools,glasser/golang-tools,syreclabs/go-tools,jdhenke/tools,golang/tools,josharian/tools,magiccao/tools,golang/tools,nicot/tools,magiccao/tools