We should only issue an error for a goto over a var declaration.
    
    The test case for this is already in the master repository, at
    test/fixedbugs/issue8042.go.  It just hasn't been copied into the
    gccgo repository yet.
    
    Fixes golang/go#19089
    
    Reviewed-on: https://go-review.googlesource.com/91696

From-SVN: r257375