all: add canonical imports

optimize/functions/validate.go

@@ -8,7 +8,7 @@
 // We encourage outside contributions of additional test functions that exhibit
 // properties not already covered in the testing suite or that have
 // significance due to prior use as benchmark cases.
-package functions
+package functions // import "gonum.org/v1/gonum/optimize/functions"
 
 import (
 	"math"