Shifting by signed types is a new language feature in Go 1.13.
    
    This requires a patch to the testsuite.
    
    Updates golang/go#19113
    
    Reviewed-on: https://go-review.googlesource.com/c/gofrontend/+/190977

	* go.test/test/fixedbugs/bug073.go: Update for language changes.

From-SVN: r274755