strings: add Bernardo O'Higgins example

R=r, bradfitz
CC=golang-dev, rogpeppe
https://golang.org/cl/5673049

src/pkg/strings/example_test.go

@@ -93,10 +93,12 @@ func ExampleReplace() {
 // ["a" "b" "c"]
 // ["" "man " "plan " "canal panama"]
 // [" " "x" "y" "z" " "]
+// [""]
 func ExampleSplit() {
 	fmt.Printf("%q\n", strings.Split("a,b,c", ","))
 	fmt.Printf("%q\n", strings.Split("a man a plan a canal panama", "a "))
 	fmt.Printf("%q\n", strings.Split(" xyz ", ""))
+	fmt.Printf("%q\n", strings.Split("", "Bernardo O'Higgins"))
 }
 
 // ["a" "b,c"]